Dripping shower head - Can't get escutcheon plate off

[slcanela]

My husband is trying to repair the dripping shower head (mobile home). When he tried to remove the escutcheon plate (on our single knob shower handle), it wouldn't come off. The set screw was removed but it's like the escutcheon plate is glued or something. The fiberglass shower around the escutcheon plate is chipping and cracking. He has repaired many dripping shower heads in stick built homes with no problem. Is there any way to remove the escutcheon plate without cracking through the fiberglass shower wall. (Our mobile home is 22 yrs old).
Thank you for any assistance you can provide, as the dripping is causing mold to build up.