Sometimes, if there's room to work it, a piece of piano wire (or a heavy gauge guitar string) can be used to "cut" the 5200 through underneath the bonded part. Get a couple of peices of dowling to make the handles so you can put some pressure on the wire without slicing yourself up. (kinda like a "garrotte" you see in spy movies)
This is a great time to address the backing plate situation - if they are not there, or inadequate, have some made and you'll have a more secure installation and fewer problems in the future.
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)