I've run into the same situation. Seems as we are putting things back together, they do not always work. Example: water pump. It seemed fine when it came off but then it had to be relaced as it seemed to hang up when it spun. Same thing with the starter. Seemed fine when we took it off but then it wouldn't start the truck, once we put it back on. It had to be rebuilt.

All those little things just seem to slow us down. Its fun but sometime frustrating when you can see the light at the end of the tunnel.