diff --git a/package.json b/package.json
index e252eea..cbe7975 100644
--- a/package.json
+++ b/package.json
@@ -15,7 +15,8 @@
   "homepage": "https://github.com/Xmader/musescore-downloader#readme",
   "dependencies": {
     "pdfkit": "git+https://github.com/Xmader/pdfkit.git",
-    "svg-to-pdfkit": "^0.1.8"
+    "svg-to-pdfkit": "^0.1.8",
+    "webmscore": "^0.5.0"
   },
   "devDependencies": {
     "@rollup/plugin-json": "^4.0.0",
diff --git a/src/btn.ts b/src/btn.ts
index 89ac15d..accda36 100644
--- a/src/btn.ts
+++ b/src/btn.ts
@@ -1,4 +1,7 @@
 
+import { text } from 'pdfkit/js/mixins/text'
+import { loadMscore, WebMscore } from './mscore'
+
 type BtnElement = HTMLElement
 
 /**
@@ -78,6 +81,37 @@ export namespace BtnAction {
     return (): any => window.open(url)
   }
 
+  export const mscoreWindow = (fn: (w: Window, score: WebMscore, processingTextEl: ChildNode) => any): BtnAction => {
+    return async (btnName, btn, setText) => {
+      const _onclick = btn.onclick
+      btn.onclick = null
+      setText(BtnAction.PROCESSING_TEXT)
+
+      const w = window.open('') as Window
+      const txt = document.createTextNode(BtnAction.PROCESSING_TEXT)
+      w.document.body.append(txt)
+
+      // set page hooks
+      // eslint-disable-next-line prefer-const
+      let score: WebMscore
+      const destroy = (): void => {
+        score && score.destroy()
+        w.close()
+      }
+      window.addEventListener('unload', destroy)
+      w.addEventListener('beforeunload', () => {
+        score && score.destroy()
+        window.removeEventListener('unload', destroy)
+        setText(btnName)
+        btn.onclick = _onclick
+      })
+
+      score = await loadMscore(w)
+
+      fn(w, score, txt)
+    }
+  }
+
   export const process = (fn: () => any): BtnAction => {
     return async (name, btn, setText): Promise<void> => {
       const _onclick = btn.onclick
diff --git a/src/main.ts b/src/main.ts
index ecd3ec3..326be46 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -2,13 +2,11 @@ import './meta'
 
 import { waitForDocumentLoaded, saveAs } from './utils'
 import { downloadPDF } from './pdf'
-import { fetchMscz, downloadMscz } from './mscz'
+import { downloadMscz } from './mscz'
 import { getDownloadBtn, BtnList, BtnAction } from './btn'
 import * as recaptcha from './recaptcha'
 import scoreinfo from './scoreinfo'
 
-const WEBMSCORE_URL = 'https://cdn.jsdelivr.net/npm/webmscore@0.5/webmscore.js'
-
 const main = (): void => {
   // @ts-ignore
   if (!window.UGAPP || !window.UGAPP.store || !window.UGAPP.store.jmuse_settings) { return }
@@ -31,7 +29,12 @@ const main = (): void => {
 
   btnList.add({
     name: 'Download MusicXML',
-    action: BtnAction.openUrl(scoreinfo.mxlUrl),
+    action: BtnAction.mscoreWindow(async (w, score) => {
+      const mxl = await score.saveMxl()
+      const data = new Blob([mxl])
+      saveAs(data, `${scoreinfo.fileName}.mxl`)
+      w.close()
+    }),
   })
 
   btnList.add({
@@ -46,49 +49,14 @@ const main = (): void => {
 
   btnList.add({
     name: 'Individual Parts',
-    async action (btnName, btn, setText) {
-      const _onclick = btn.onclick
-      btn.onclick = null
-      setText(BtnAction.PROCESSING_TEXT)
-
-      const w = window.open('') as Window
-      const txt = document.createTextNode(BtnAction.PROCESSING_TEXT)
-      w.document.body.append(txt)
-
-      // set page hooks
-      // eslint-disable-next-line prefer-const
-      let score: any
-      const destroy = (): void => {
-        score && score.destroy()
-        w.close()
-      }
-      window.addEventListener('unload', destroy)
-      w.addEventListener('beforeunload', () => {
-        score && score.destroy()
-        window.removeEventListener('unload', destroy)
-        setText(btnName)
-        btn.onclick = _onclick
-      })
-
-      // load webmscore (https://github.com/LibreScore/webmscore)
-      const script = w.document.createElement('script')
-      script.src = WEBMSCORE_URL
-      w.document.body.append(script)
-      await new Promise(resolve => { script.onload = resolve })
-
-      // parse mscz data
-      const data = new Uint8Array(
-        new Uint8Array(await fetchMscz()), // copy its ArrayBuffer
-      )
-      score = await w['WebMscore'].load('mscz', data)
-      await score.generateExcerpts()
+    action: BtnAction.mscoreWindow(async (w, score, txt) => {
       const metadata = await score.metadata()
       console.log('score metadata loaded by webmscore', metadata)
 
       // render the part selection page
       txt.remove()
       const fieldset = w.document.createElement('fieldset')
-      metadata.excerpts.unshift({ id: -1, title: 'Full score' })
+      metadata.excerpts.unshift({ id: -1, title: 'Full score', parts: [] })
       for (const excerpt of metadata.excerpts) {
         const id = excerpt.id
         const partName = excerpt.title
@@ -97,7 +65,7 @@ const main = (): void => {
         e.name = 'score-part'
         e.type = 'radio'
         e.alt = partName
-        e.value = id
+        e.value = id.toString()
         e.checked = id === 0 // initially select the first part 
 
         const label = w.document.createElement('label')
@@ -117,13 +85,13 @@ const main = (): void => {
         const id = checked.value
         const partName = checked.alt
 
-        await score.setExcerptId(id)
+        await score.setExcerptId(+id)
 
         const filename = scoreinfo.fileName
         const data = new Blob([await score.savePdf()])
         saveAs(data, `${filename} - ${partName}.pdf`)
       }
-    },
+    }),
   }).title = 'Download individual parts (BETA)'
 
   btnList.commit()
diff --git a/src/mscore.ts b/src/mscore.ts
new file mode 100644
index 0000000..59f40a2
--- /dev/null
+++ b/src/mscore.ts
@@ -0,0 +1,30 @@
+
+import { fetchMscz } from './mscz'
+
+const WEBMSCORE_URL = 'https://cdn.jsdelivr.net/npm/webmscore@0.10/webmscore.js'
+
+export type WebMscore = import('webmscore').default
+
+const initMscore = async (w: Window) => {
+  if (!w['WebMscore']) {
+    // init webmscore (https://github.com/LibreScore/webmscore)
+    const script = w.document.createElement('script')
+    script.src = WEBMSCORE_URL
+    w.document.body.append(script)
+    await new Promise(resolve => { script.onload = resolve })
+  }
+}
+
+export const loadMscore = async (w: Window): Promise<WebMscore> => {
+  await initMscore(w)
+
+  const WebMscore: typeof import('webmscore').default = w['WebMscore']
+  // parse mscz data
+  const data = new Uint8Array(
+    new Uint8Array(await fetchMscz()), // copy its ArrayBuffer
+  )
+  const score = await WebMscore.load('mscz', data)
+  await score.generateExcerpts()
+
+  return score
+}