Nipping up like that indicates there is a lack of end float on the crank for some reason. One of the bearings must not be fully home
Just had another look at it and noticed the top seal had a gap when looking at it from the top side, I just installed it flush with the casing on the inside. Tried hitting the seal further in till it closed the gap on the top side and installed the bearing again and refitted and that solved the issue. I got worried that the case halves had no clearance but crisis averted. Will need to pay attention more next time how far seals and bearings are installed before disassembly.
