Check the board for bad solder joint at the connector.
http://www.pinwiki.com/wiki/index.php?title=Bally/Stern#Failed_Lamp_SCRs
For the not working lamp, check Q29 (2N5060 or 2N5064)
http://www.pinwiki.com/wiki/index.php?title=Bally_Playboy#Lamp_Chart
Also very nice is a Tech Chart with everything on it.
http://www.pinballrebel.com/pinball/cards/Tech_Charts/Bally_Playboy_Tech_Chart.pdf
Peter
http://www.inkochnito.nl for score and instruction cards.