Annie, I have one of the Jumbo 150 and it is nice. Yes you can get a replacement pad (I think Calumet carries them) and they also sell a platen cleaner. I have read of others using oven cleaner to clean the surface, but can not say one way or the other. Mine needs a good cleaning and a new pad would not hurt either. I have done some mount work with mine and had very good success with it, just using the mat board sandwich, and release paper to keep it from sticking to the board.
Depends on how 'good' a deal the seller wants to make you, these show up pretty often at e**y, do a search from the main page, they are used for many different purpose, so they show up in many places.
Sorry, mine is a 160 the later version, the lastest is the 160m...the pad should just lift out and you place the new one in.