Starter not engaging sometimes

I recently acquired a 340 4 speed Demon in the summer of last year. Since I've had it has had an issue where the starter will not engage fully and grind a bit but then will engage on the next try. This happens maybe 1 out of every 10 times I turn the key. I took a look at the starter today to see if everything was tight and it was but I did notice that the front dust cover was missing (between the starter and bellhousing). All the teeth I can see on the fly wheel look good. I know it is thin metal but is it possible not having the the dust cover between the starter and the bellhousing cause the starter not to engage fully sometimes or is my starter just bad?