http://www.pinballrebel.com/pinball/cards/Tech_Charts/Bally_Skateball_Tech_Chart.pdf
Look at the tech chart to the lamps that are having issues and see if they're all on the same 4514.
https://www.pinwiki.com/wiki/index.php?title=Bally/Stern#Controlled_Lamp_Problems has the U-1-4 assignments as well.
All the lamp test does is turn all of the lamps on and off and all 15 nibbles are sent one after the other to the lamp driver boards' latches, regardless of if they're on or off. It always takes the same amount of time regardless of if 1/2 are on, 1/4 are on, all are on, off, etc.
