I just bought a 20 year old boat trailer. Last week end I tried to check the bearing grease, but a bearing looked bad. I could not replace the bearing because the axle was bad. I could not replace the axle because the nut on the U bolts [that clamp the springs, saddle, and axle] were rusted solid.
I used a hammer, a torch, Kroil, a hack saw, a cold chisel, wrenches with cheater bars, and 10 hours of sweat to get the U bolts off.
This week end I launched and noticed the rollers did not roll. Now there are more frozen nuts I have to get off to replace the rollers and add more rollers. I ordered new rollers from MarineEngine.com I ordered a Sawzall clone from Harbor Freight. I ordered stainless nuts and bolts from Enco.
I hold boat trailers way up there, with hot water tanks that flood the basement.