I reinstalled the battery and all its connections. When I tried starting the engine last weekend I sapped a lot of the battery voltage from it, so I took it out and recharged it.
The Ztron switch/breaker unit that I had, had a failure last weekend, apparently because of the kind of starter solenoid. Below is what the manufacturer sent to me. I am waiting for the unit's return, but didn't want that to stop me from test starting the engine, so I simply disconnected all the non-essential electrical like radios and lights, and added jumper wires (where switches had been) for the coils and the starter. Those are the loops of red and yellow hanging down in photo 1. That should be fine for a test run.
The old pair of jeans in photo 2 are there to keep thosd non-essential (+) wires from touching the aircraft metal and causing shorts.
Your solenoid is the type with the 4th terminal connected to case to ground.
A diode is needed across the solenoid positive control terminal (that which you hooked up to the BP8X) and the battery input of the solenoid. The diode's negative (cathode / line/bar symbol) is connected to the battery side, while the diode's positive (anode / arrow) is connected to the control terminal. This reverse connected diode shunts the dangerus high voltage spike generated from the internal coil into the battery side (which can absorb the energy).
I will send you a diode and instructions with your repaired unit.
Battery and all leads reinstalled.
Red and yellow loops are connecting wires that used to have a switch between them.
For the first time in its life, the plane is sharing garage space.