IF the parts are available. My under-warranty new furnace needed an eductor fan -it still worked but was very noisy. None of the dealers had it in stock - and nor did the distributor. It was going to be a 3 week minimum wait - so I just took it out and brazed the hub where the blower wheel was (supposed to be) fastened to the shaft.
20 minute job, about a buck's worth of brazing rod and gas - and it's been perfect for something like 8? years.NO maintenance contract would have managed to solve the problem in less than 3 weeks.