diff --git a/service2.js b/service2.js
index a3d6773..24e5166 100644
--- a/service2.js
+++ b/service2.js
@@ -790,7 +790,7 @@ class BesCKService extends BesTreeService {
    * Unregisters grammar checking service.
    */
   unregister() {
-    // TODO: Undo `this.ckEditorInstance.model.document.on('change:data', this.onChangeData)`.
+    this.ckEditorInstance.model.document.off('change:data', this.onChangeData)
     this.restoreCKEditorSpellcheck()
     if (this.timer) clearTimeout(this.timer)
     super.unregister()
@@ -840,9 +840,8 @@ class BesCKService extends BesTreeService {
   disableCKEditorSpellcheck() {
     this.ckEditorInstance.editing.view.change(writer => {
       const root = this.ckEditorInstance.editing.view.document.getRoot()
-      // TODO: Get true original CKEditor spellcheck setting (writer.getAttribute('spellcheck', root)?).
-      this.originalCKSpellcheck = 'true'
-      writer.setAttribute('spellcheck', 'false', root)
+      this.originalCKSpellcheck = root.getAttribute('spellcheck')
+      writer.setAttribute('spellcheck', false, root)
     })
   }