Horwith Freightliner would be my second choice for service work.
Next door is a Cummins/Cat/Detroit/Onan certified engine shop called Engines, Inc. Ask for either Mark or Bob. They will do complete service on the chassis and engine and trans for you. Been using them for over ten years now. Depending on where you are on the mileage of the unit, you might want to have the valve train run also at the same time.
Hate to ask, but where is that coach on tires?? Especially if it has sat for a few years with minimal use. There are one or two really good tire shops not far from Northampton with good tire pricing.
2010 American Coach Revolution 42w; carrying 2014 HD Electra Glide Limited and towing 2015 Chevy Silverado 2500HD.
Dirt's for racing and asphalt for getting there.
410 Sprint Car's rule!