I did a Funhouse the other day and it was quite easy - put the machine in the sun for 1/2 hour, and just peeled it (extremely slowly) still in the sun - very slightly lifted two corners of clock numbers inserts and that was it.

Then took it straight inside and used De Solve It citrus spray and scraped the playfield with an old credit card to get the bulk of the residue off (needed to do this a few times), then shellite, novus etc