Can anyone refer me to a means by which I can service my HDA-300? A local welding sales/service agency can work on it yet they cannot guarantee parts availability. This is old school technology and primarily transformers. I would think custom transformers could easily be ordered if necessary. The electronics is quite simple but there may also be specialists that can meet these needs as well.

Please let me know. I have been fortunate to be able to move on to an inverter tig welder and I have offered to give my HDA-300 to a co-worker.
I am not interested in giving him junk. The unit worked when I purchased it many years ago. However, it has sat in my attached garage since with little use. Condensation is not likely to be a friend in this regard.