[B_and_D]

It sounds like there may be something sticky or dirty underneath that's causing this (where you can't see it). We recently pulled out the bed for repairs and in our model (2720) there is about a 10" area at the end of the lower TM box that never sees the light of day unless you pull out the bed.

Pulling out the bed is not too difficult, we just unscrewed about 10 screws from the plastic strips that guide the bed supports and popped out the supports. If you do this, make a mental note of where the washers were (or take a picture) so you can put them back correctly. It's definitely a 2 person job.