If you have an older front load Maytag dryer that starts to rumble like a freight train with a square wheel...don't despare. It is likely this easy fix: ( I have done this on electric & gas dryers)
Access the blower wheel by removing the front cover. Check to see if the spring clip that holds the blower wheel tight to the shaft is sprung loose. (I have found several that were.) You can get a new spring clip, or use a small worm drive hose clamp to replace the clip. DO NOT OVERTIGHTEN the clamp. It only needs to be snug enough to drive the blower. Its supposed to slip if a foreign object gets in there...like playground gravel, or a golf pencil.
Carefully replace the front cover, being sure to get the drum properly aligned, and all the felt seals flat. (A helper is really handy here.)
This has saved my butt a few times.