Searching for Inside post is too long for replacement handle 40-150

Taking a look inside the 40-150, the hole it looks like it could be slightly tapered at the bottom. I suggest inserting the spindle into both the 40-150 and your original handle to see what the length difference is between the two of them. You could then try and file your spindle a little to allow it to go deeper into the 40-150 handle as per that difference.