I get all my pf's cleared and never had a problem, to the point now that
when I buy my own personal pf's they go straight to either Bill Davis or Chris @highendpins
if there 2nd hand playfields they get touched up and cleared,
and if l score a  NOS playfield they still go and get Cleared   

(those NOS Sega and late model Gottlieb playfields are eye popping when they get a Wms style clear applied to them)



while I must say that I have been warned that "milking" can occur at the inserts
this has yet to happen to any playfields that I have had done ,  I would probably be reluctant
to cc a older game but as far as (very) late  80's and up to 1999 yes I would always clear coat

if your interested in trying clearcoating your self Marty then l have  a NOS AlvinG world tour pf
that l would be happy to give you if you want to try on that?