Mr. 924s

I've already installed 2 new starters on my 1987 Porsche 924s in the past week. The first starter was a rebuilt one from NAPA and when I put it in, the ring gear damaged the starter drive completely because the pressure plate ring gear bolts were loose so I went in and tightened them according to manufacturer torque specifications 18ft-lbs. I then returned the damage starter and decided to purchase another starter from Bosch; installation went well BUT now I have another problem every time I start-up the car, I hear a grinding noise coming from the NEW starter it sounds as if the gears from the starter are not disengaging from the flywheel? I’ve already inspected the ring gear on the fly wheel and there are no broken teeth. The juddering/grinding noise is about 1-2 seconds long and it only happens during startup then it goes away? Any ideas why this might be happening? I've also attached a picture of my installation, are my connections correct?

Dante924S

I have also replaced my starter and I have this same problem. For the life of me I cannot figure it out! Did you ever find out this problem?! I have checked my connections at my battery, replaced my plugs and plug wires, as well as my distributor rotor and distributor cap. Any ideas?!