[911buff]

I have a ‘71 911T that is giving me starter issues. Pulled the starter and had it checked and the selonoid was bad so I replaced with new starter. Worked great for half a day and now again car will not start. When I turn the key to the start position, power is being pulled because I can hear the fuel pump bog down. If I cross the terminals on the starter, cranks over hard. So, unless that selonoid is bad (haven’t had a chance to pull it and test it) I am guessing it is the switch. My question is how to trouble shoot the starter switch. Can I cross the 30 terminal to the 50 terminal on the plug? Or is there another way to test to determine whether switch or starter? Thanks