Hi Mike
There are several RV salvage yards. Probably the best known is
https://colawrvsalvage.com/. I looked quickly but did not see a listing for Aqua hots, but I suspect they have them. They have typically been "proud" of the parts they sell.
There are folks that "repair" Aqua hots. Most are geared towards service type work.
Aqua Hot has great manuals and most of the repairs can be be done by a knowledgeable RV Tech.
The boiler is heated with a Webasto DBW 2010. That is a fairly common unit that probably has many service options.
They have two different control systems. I have the system that does not use a control (circuit) board. As such, it is pretty straight forward to trouble shoot and repair.
One of the problems that makes folks nervous is the heat exchanger. The typical failure is a broken tube due to freezing. There are folks who have taken the exchanger apart and installed new tubing. It did not look like too bad of a job.
Since you are in Canada, I am not sure what your options are. Aqua Hot is a Colorado company and they may have a rebuild option.
Jim