Topic: We kill starters on a regular basis.
We've gone through 4-5 so far. Usually it happens at a race. We pit, we fuel, we crank, expect the crank step does not work. Fortunately the car push starts easily. The Judges have push started us numerous times.
Once I killed a good starter in my carport. After an engine install I did the 20 minute cam run-in and that went well. Turned off the engine, did some odd jobs, and tried to start it again. The starter would engage but not turn the motor. I feared the motor has seized. I bench-tested the starter and it spun. I tested another starter and it spun much stronger.
In general first signs are weak cranking or even having to push start the car. After things cool off the starter is fine again, but not always. I'm not getting the click-click of a weak solenoid.
Heat is probably killing the starter. This happens on my Tahoe where the starter is near the exhaust, and it gets a new starter ever two years.
Odd thing is the starter on the Opel is away from the hot parts of the engine. It's on the driver's side. The exhaust is on the passenger side. How is it getting enough heat to be damaged? Should I water-cool my starters?