Could I make a suggestion here....
The attached image shows the wiring on a typical Chevy starter motor....shown on the rear of the solenoid
There are three electrical cables on the solenoid...the large cable n the center is the battery cable coming down from the junction block,,,lets say that cable is at 12 o'clock....
Located at approx 3 o'clock is the Start wire that comes down from the ignition switch start terminal....(dont worry about the one at 9 o'clock right now)
Measure the voltage present at the main cable 12 o'clock...it should be 12 v...regardless of whether ign is on or not.
If it measures 12 v...move to next step....if it doesnt show 12 v go back to the junction block and test voltage at both terminals...they should both show 12 volts.
With the ign switch turned off...Take a small jumper lead powered from the battery positive terminal and touch it to the terminal on the solenoid at 3o'clock position....if the solenoid engages the starter should crank the engine.
If the solenoid engages (click sound) but the starter does not turn the engine, the starter or solenoid is most likely faulty.
If solenoid and starter work correctly using the short jumper lead, there is an issue between the ignition switch feed or the switch itself...
You mentioned a scenario where moving the wires would cause the starter to crank but the engine not start...I suspect the feed wire down to the solenoid is receiving a 12 volt cross feed from another wire...most likely due to chafing...
If the solenoid has failed...Amazon has them under
https://www.amazon.com/Tru-Tech-SS20...t%3Ac10+pickup
or try your local parts store...most folk tend to replace the starter unit...your choice
Hope this helps...Bill
