bad Voltage regulator ground

[chargerjy9]

pulled car out of storage, had to jump start it, drove home, put on trickle charger. Started car, fired right up. drove it,parked it for 2 hours, started right up again. on way home noticed turn signals were sluggish and h lights were dimming, Alt gauge showed discharging at idle. got home put in garage wouldn't start. hooked up battery tester batt showed OK, Alternator showed OK. Batt and alt relatively new.. thinking was bad Volt reg. took it off. Self tapping screw upper right was loose wouldn't tighten.(each of the attachment screws is a different size BTW.) Is that a ground for the V reg? can I use a bigger self tapping screw that will tighten more securely, or might there be a different issue?

[PlainfieldCharger]

You should remove the voltage reg from the firewall and clean any rust or paint under the mounting points. If the screw is stripped out maybe you could put a 1/4 bolt in it with a nut on the back to make sure it does not come loose(go in though the glove box opening). I personally ran a separate ground wire from the back of the intake manifold directly to the Reg.
What was the voltage at the battery while it is running?

[71 SE3834V]

Is it the 3rd gen in your avatar?
Yes it needs to be grounded well. One of mine was stripped also but rather than going to a larger screw I added a nut to the back side as mentioned. There is access to the backside through the cowl screen. Easy.

Yeah, weird. Mine had 2 different sizes of heads on the screw also.

[John_Kunkel]

When you encounter a stripped out sheet metal screw it's best to install a nut insert in place of the hole. Kits to install them are available from Harbor Freight.

http://www.harborfreight.com/45-piece-threaded-insert-riveter-kit-1210.html