Starter only cranking halfway

[delphis]

so I have my 89 beater coupe that I go out in the back and start up every other week or so, normally it would take a few keys turns to start it (replaced starter and upgraded ground cable) but when I went to do it today I was only getting half a crank and it seemed like it was going really slow, and I would occasionally here a very fast ticking. I busted out my portable jumping system thinking it might be a low voltage on the battery, but I let that charge for about 15 mins and then tried it again and the same issue. now I did some research and figured since I don't DD this car that there might be an issue with a bad ground to the engine? is there a specific spot to check for this as I have become mostly familiar with my sr.

thanks
timmay