That's awesome Guy, the forum thanks you.
I took the operator cover off this morning, and set to checking all TBs, all connections, and to bathe the S8 in deoxit, like it was visiting a Turkish spa. I found two wires on a TB that were not loose, but could take an additional 1/16th of a turn. I thoroughly sprayed the S8, and let flare off.
I wheeled the set back to my testing area, threw the top back on, and let it get up to temp (nothing moves too quick in -18C, myself included). I proceeded to put load on it, and I think we have success. It took 10.8kw with no sign of stopping, and I ran it at the full 13.5kw resistive for 20 minutes, and she is still purring.