FYI: The air bearing is the heart of the Maplenoll Line. The bearing plates are 8" in diameter and are the same in construction, alloy and design for all models. The bearing plates are incredibly simple in operation: The top plate spins supported by air pressure(PSI). The bearing consists of 3 parts; the two circular plates(top & bottom) and one plastic center pin located in the center of the bottom plate that aligns that plate to the top plate. The bottom plate is afixed to plith and does not spin. Should these parts be damaged ,the Maplenoll Record Player can not operate.
In my opinion never buy a damaged maplenoll, except for parts. Before purchasing a Maplenoll make sure the air bearings are not damaged, out of round or lacking a center pin. Be aware,the center pin's are made plastic and they are ageing. The center pin is the weakest-link of the Maplenoll Record Player and is the actually "inner-heart" of the table. Without it regardless of the condition of the plates , the table will not operate. The air bearing uses between 3-5 PSI to fuction(all models), thereby leaving the rest of the air pumps output for the hi-pressure manifold that operates the tonearm.
The costs associated with the remaking of the bearings is probably more than the cost of the table; the center pin will cost hundreds for a shop to manufacture due to set-up time, the material is relatively cheap to the other associated costs. What ever one does as a owner treat these parts with respect, without them nothing works and you investment could be lost.
In light of the fact these tables are approaching 30+ years old, I want the buyer to appreciate what's important before the cash outlay. Please keep this in mind : Given a lot of TLC and patience , most Maplenoll's even basket cases can have a new lease on life, provided all the parts are included at sale. And for those 'Nolls in excellent condition , they could operate forever. All Maplenolls require some hands-on work but generally operate well after set-up.