Putting together the crankcases, when I tighten the bolts the crankshaft gets stuck/so stiff it can barely be moved. I've taken the cases apart numerous times, but can find anything that would cause this. The only thing I can suggest is the upper crankcase pushing down on the crankshaft, but that wasn't happening before? And there was little-no gasket cement when I initially took it off.

This has cost me 2 days of work on an already limited timeframe so any help would be much appreciated

Putting together the crankcases, when I tighten the bolts the crankshaft gets stuck/so stiff it can barely be moved. I've taken the cases apart numerous times, but can find anything that would cause this. The only thing I can suggest is the upper crankcase pushing down on the crankshaft, but that wasn't happening before? And there was little-no gasket cement when I initially took it off.

This has cost me 2 days of work on an already limited timeframe so any help would be much appreciated

did you put in new bearings, and are they the right colour for clearance?

are the gears in correctly as they can bind the case and thus the crank

Sometimes after cases are reassembled the crank can be tight/stuck. A light smack on either end with a brass hammer will usually loosen it up. Don't use anything that could damage the threaded ends of the crank. If you have checked everything good this is likely the problem.