snclap2,
To me, the air bellows are somewhat of a false concern in that they are not super expensive and do last for a few years or more. The problems are the valves, compressor, lines etc. They too are "simple". You can still get all of the o rings at the dealer. But it is taking the time to trouble shoot and find the problem, remove the problem,rebuild the problem and re-install the problem. I had a great mechanic here in Ga. who passed away a couple of years ago. Since then I have been writing checks because of " Oh yeah! I work on them all of the time" Mechanics who charge $60.00 and up an hour to "diagnose" the problemand end up replacing half of the system because they can't find the problem. So I bought the shop manuals and some tools and it is a joy to work on. But there is a reason my daily driver is a diesel!

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"BECAUSE KNOWING IS HALF THE BATTLE"
G. I. JOE.