I've only seen Gel-Gloss recommended in one post on a bingo web site, but I tried it and will use it again. My games are 1950s EM.
http://bingo.cdyn.com/techno/overhaul/playfield/surface.html
http://ballybingo.fff.yuku.com/topic/547/product-recommend-cleaning-dirty-playfield
Read the final post in the second thread.