I assume Q14 is the driver transistor by the schematics? I don't own RBION but it sounds like you should replace the transistor if jumping it solves your problem. Could be partially damaged so it has more resistance than it should between the doped layers in the device and is not allowing full current flow through.

Those are almost identical transistors spec-wise.. except that you have a much higher driving voltage threshold on the one that the manual calls for -- 100v vs 60v for the one you have on hand. The flipper circuit should be running around 50 - 60v so the one you have on hand is probably fine if you want to try and fix it right away. The max continuous and pulsed current specs are only 1amp off between the two so unlikely that would cause any problems. No promises though.. if you're not in a hurry I'd just order a few of the correct ones. If you want to try to fix it right now, go for it but no promises

Just to clarify -- the flipper is initially strong but it won't stay up when the circuit switches to the holding current or is it weak even when it's "flipping" ?

Good luck! Def. a voltage/current problem with no EOS switch there. I wonder what the voltage is measuring when the flipper is activated and holding?