Hi Matt, These things come in different configurations, but I believe most can be replaced from underneath. There should be a screw that also releases the fan motor and all to come down, with another plug for it's motor. this may allow you better access to the fan motor. I've oiled ours many many times, it helps a lot for a while but needs re-doing from time to time.
I use regular 3 in 1 oil, think it penetrates and lubricates better and longer than wd40, but you have to have access to the motor shaft where it enters the motor's bearings. Usually once you get the fan out, it looks like a box mounted to the joists with nails or screws. I think one could remove that box, find the wiring where there are presumabley wire nuts to remove, get the whole thing out possibly excepting the top cover and vent hose, and take it to the local building supply to get one that would be the best match. Of course you never get an exactsize match, so who knows what kinds of struggles you might have to go through to get the new one in. If you can get at the motor, do what I do, and just oil it when needed. I've gone so far as to remove the fan blade from the motor shaft, it's just a jam fit, and literally wash the blade with soap and water. It helps the blade to be less grungy and have better ballance. good luck Tom Fowle
