I have a Pioneer RT-1011L I bought new back in 1979. Had a fair amount of use years ago, but the last several years it has sat idle. Recently I played a tape for about 20 minutes but I could smell overheated electronics so I shut it down. The swing arms on both sides have gotten very stiff and maybe the motors need attention too. How do I lube/ clean this stuff (any web sites describing such?)? And other maintenance it might need? One of the swing arms got stiff when the machine spent overnight in the cold winter in a moving van.

You need to take the rear cover off and see what is cooking, if the deck has been sitting for a long time maybe dust ? :smoke:
Does the reels turn ?

Was the deck sluggish when it began to smell? The motors are easily overheated when they are forced to conduct excess current. Try this. Hold the shut off arm in the on position with a rubberband. Power up and let the capstan spin. Monitor the capstan motors voltage and feel the motor after a few minutes. It should get warm. Not hot. It's also possible that the odor was dust in the machine. Check to see if there is dust or dirt surrounding the PCBs. Try to pinpoint which, if any components are overheating.
I open the motors on my Teac machines about every 10 years. While in there, I clean the bearings and reoil them. The oil has a tendency to "fuse" to the bearing due to heat. I've repaired machines where the owner used 3-in-one oil instead of the recomended type. The oil and heat formed a ring, like the ring around Saturn. The dried oil was very hard to remove.
Ron

I usually take a paint brush and gently vacumn out the dust that collect inside. While I did not take apart the motors on my last reel to reel project, a 1230 I oiled it with factory TEAC oil I had laying around here. Let us know if the motors gets hot. I would like to know. As stated, they should get warm but not hot. I you need to take a motor apart they are not bad. Took a Teac 4010 capstan motor apart once years ago.

Good luck. Sold those deck new. A nice collectors deck. Got too many but would not mind have one :D

Eric