Lately it's been hard to get my boat on and off of trailer so today I took a look at the rollers. They look OK but are hard to turn. I focused my attention on the 2 rollers furthest back which are held by a pair of brackets. I assume they should freely turn on the shaft, however these are fused to the shaft. These particular rollers are Stoltz 12" keel rollers. Can I salvage the rollers and get new shafts or will it be impossible to remove the old shafts?