Go ahead and pull the upper flipper apart - clean the plunger link and coil stop with rubbing alcohol. Is the coil sleeve (tan colored plastic thing that fits in the coil) all gunked up? It should be replaced - they cost .20 each.
I'd still recommend springing for the rebuild kits for both lower flippers and the upper. It's $40 well spent
http://www.pinballlife.com/index.php?p= ... parent=172Get 1 full kit, and one "right side only" for the upper right flipper.
It'll change your life man . . . swear to god.
Before you rip the pop bumper apart, make sure the switches make contact when you push the plastic skirt down (do this with the PF up). You might put some rubbing alcohol on a business card and rub it between the contacts of that switch.
If it's not that, you may have a transistor that needs replacing - check that other crap first though.