After isolating the battery case yesterday with some large rubber sheets I had laying around, the +13V I measured between Battery Positive and Frame dropped to 0. However, it didn't resolve the tilt issue, as you guys indicated.

Since I'm still no wiser as to why the tilt works when the solenoid gets 7.1 V from a random power lead and doesn't work when it gets 7.0 V from the wire that's intended for it, I'm just going to order a new solenoid coil and o-ring kit for SV1, it won't run more than $70 total. I'll report back.

In the meantime, I'm able to use the lift normally by extending two capped, unused wires to the tilt solenoid. When the key is on the positive lead provides 7.1 V. The wires are #547 and #2993, I can't find anything in my manual about them. They do not provide power when the key is off, which is good.

Most surprisingly, Tilt Lockout still seems functional when the solenoid is supplied by those wires, as I cannot go above Staging height when tilted far forward, and I cannot tilt far forward when above staging height. Go figure! I'm surprised.

Thanks for all the advice!