Hi swampy . Mate seeing as though you've recently had the whole playfield out of the FT while you re-decalled it , it could be a loose wire on the coil that fires the ball across to the main trough . Sometimes when moving things around the wires can work free and break off at the solder joints on the coil.

The VUK problem sounds like something similar in that something may have moved when you had the pf out . Is there a switch that activates when the ball is there or is it opto's . If it's a switch then check that it's not closed all the time (ie. the game will think there is a ball sitting there) . If it's opto's then give them a clean with some metho or isopropyl alcohol on a cotton bud . Also check both for loose / broken wires .

You may have already checked these but thought I'd throw them in just in case .