Removing decals from playfield inserts

[48]

Wondering how to go about this?
Have a playfield with lots of inserts on it and need to replace all the decals, several of them have wear, and no point in just changing a few.
There are about 5 inserts that I need to remove due to being uneven, so no real drama removing the decals from those ones, but my question is, how do I go about removing the ones off the inserts that are still level?
Hoping I don't have to remove all the inserts, as there is a chance some of them will get damaged in the process.
Anyone have a good method of getting the decals off without damaging anything in the process?
They are still well and truly stuck down, can't seem to find an edge to lift easily.
Any tips from those that have done this?
Its my first playfield restore and while I have to learn somewhere, I don't want to bugger something unnecessarily.
Cheers,

[MartyJ]

Unless the playfield has had 'decals' fitted on inserts previously, they are actually screen printed directly onto the insert.

In the past for games I've done (1990+ WMS machines) I strip the playfield, heat and remove the actual insert, wetsand level and clean then replace.  Touchup around bordering, apply decal then you should either mylar or clear coat over the top.

[48]

Thanks for the quick reply, guess mine has been previously done then, as they sort of chip off with a razor blade or similar.
This is the case even under the (what I assumed was) factory Mylar.
Starting to look like I have to knock out a crapload of inserts.