I've found something strange with the new hoist I'm setting up. On the very longest legs there are large casters pre-assembled on those legs in the box. Then in the box came 4 casters. 2 That are large (same size as the front probably) and 2 that are pretty small. After I assembled it, those small ones that I installed are dangling in the air....in the middle position near the main upright post (mast). Manual shows all the parts and says 4 casters but doesn't say anything about size or how to install them, so I assume they should be the same size...the way they have all the bolt sizes and all - the casters are lumped together saying "4". I've noticed a few errors in this owners manual already. Should I go back to the vendor and ask them to supply me with 2 more large ones so I'll have 6 total the same size? Or are the small ones there for a reason. I would think 6 equal size would be more stable no? I found this online but it's not the same model hoist. http://autorepair.about.com/od/tools...st_asbly_3.htm This write up says to install the small casters at the very back.