How can one check for broken teeth or warpage on flex plate.
I just change the starter on my 240 1986 and the starter sometimes spins
very fast without cranking the engine and sometimes works properly.Its like playing russian roulette except that one can lose more than once.
Apart from taking out the stater and cranking the engine manuallly is there a way to have a peek at the flex plate and check it for broken teeth or warpage.

It sounds to me like you need to take out the starter anyway...

One cause for this problem is a buildup of gunk where the starter gear doesn't slide freely on it's shaft, which can result in the problem that you describe. You should remove the starter, clean the shaft, and check for broken teeth on the flywheel. I had an '87 240 where the starter would come on randomly while driving, due to bad wiring. It resulted in several chipped and half-missing teeth on the flywheel, but no damage to the starter gear. So apparently the flywheel teeth are more fragile than the starter gear teeth... go figure.

In any case I think you can also get a view of the teeth by taking off the bracket which the bottom 2 transmission mounting bolts attach to... you would have to remove those two bolts as well as the 4 bolts that connect the braket to the bottom of the block.

Does the advice to check through the transmission apply to a standard or automatic