My 1970s era Fridgidaire electric dryer stopped heating up. I looked inside and saw one of the wires to the heating element was disconnected, where the wire had attached to a coupler. The coupler had a ring between two nuts on a bolt which went through the metal tube containing the heater element and attached to one and of the element wire. I reattached it.

Now it works great but the upper of the two bolts gets so hot it glows red.

What's going on and how can I fix it? Thank you!