Remove the starter, check for a ground or loose wire touching a lead on the solenoid first.

Since you have the starter off, spend $12 and 10 minutes and change the solenoid.

Should cure the problem.

Find the cause before you go looking at changing starters. Not necessary to get a mini starter, a $15 heat shield will suffice or change to a high tension GM spring specifically designed and sucessful at curing heat soak issues.