DC blower motors usually do fail due to bearing failure caused by seal failure and loss of lubrication.
When a replacement motor is unavailable or excessively costly it is possible to disassemble the motor and lubricate the bearings. I have done this several times on cars, trucks, and ag equipment, though never on a furnace. My experience has been that it doesn't always help (sometimes the bearings are too far gone for lubrication to help), and at best it's a fix that will last a few years. After all, it's the seal failure that led to the problem in the first place, and squirting some oil in there doesn't do anything to fix that.
I had a planter (for corn) that had individual electric blowers for each row to provide air for the metering system. I ended up drilling holes on the outside of the motors so I could drizzle in some oil every year. It worked out OK but then the motors were easily accessible.
I'm guessing Skater's rv tech may have re-oiled the bearings for similar reasons. It can be nearly impossible to remove a badly rusted blower wheel without damaging it and without a replacement wheel in hand it would be tempting to take shortcuts.