91 tracker timing problem

Had a timing belt go out and after replacing have had a difficult time keeping it timed. The key and keyway are worn and won't allow the timing to stay in place. Has anyone encountered this and is there a fix other than total replacement? Welding key in place or anything else?

Hi. Have a 90 with same problem, timing gear on crank has worn keyway on the crank AND especially on the small cogged timing gear, possibly due to miss firing or something. I had low compression in #2 cylinder so have had the head re-done. To fix the worn crank, my friend used a dremmel tool to cut a slot in the crank, then bought a long straight key and ground it to fit in the crank and also in the timing gear (I had bought a new timing gear), and after putting the gear on the crank, he tapped the key into the slot and reassembled the engine. I've driven it for several days, but today the water pump belt broke; I hope they are not related. The engine seemed to work fine with more power. Hope this helps. The garage told me the engine was shot, but this seems to work. Good luck.