Finally I lightly filed the flipper button contacts, they had become dirty over time, the game then played 100% stronger. Those switches send power to the coils and are some of the few switches that need filing eventually.
Nothing worse than weak flippers on a pinball machine. I always replace the flipper button switches, get rebuild kits for all flippers, replace the coils (yes, yes... everyone says they never go bad and don't make a difference... well, in my experience, the flipper is stronger with new coils...at least in my brain), and don't forget new flipper bushings that don't come with the rebuild kits. Get your eos switches set correctly and get the gap between the flipper bat and the bushing set correctly (not too tight or it will bind up, not too loose or it will be sloppy)... I just use my trusty "flipper tool" for that gap.
My last Whirlwind had the same treatment and never had an issue getting up the ramp. It went up with ease on every shot. It is a little cash to put into it, and arguably overkill, ...or is it??? I mean ya know??? Playing a pinball machine with weak flippers just plain sucks.