hook the shifter back up, leave the cables loose at the engine, try to operate the shifter with some one putting a little resistance on the cable ends and see if it gets dramtically harder to operate. If it feels pretty good, hook up the shift cable only at the engine. Start the engine and check how it shifts(don't shift it with out the engine running, it can bind teh cable), if the controll box feels pretty good, then install the throttle cable, make sure you don't preload the throttle cable more than 2 or 3 turns, max. If you have the throttle cable preloaded too much, it will cause the controll box to be stiff. If it is stiff with just the shift cable hooked up, disconect the shift cable at the bracket and try to shift teh cable to the drive by itself, it is normally a bit stiff, but you should be able to shift it with your hands. The slave cable to the drive can go bad for a various reasons, and they need changing out from time to time. Just try to separate the shifter from being the problem for now(we can discuss shift cable replacement later). Those shifter are not that great of a shifter, don't even try to service it, it will get you into more of an issue than you could imagine, when they were new, they were not that smooth. If you think you need a replacemnt, try with Uflex or Teleflex, check Iboats or ebasicpower.com