I have cleaned the original relay in several TR-4Cs without
success, Tom. Gary, K4OAH sent me the info on a fix.
You can get a plug-n-play replacement
that has gold contacts and works well for $17 plus
shipping from:

P&B R10-E1-Y4-V2.5K.

Mouser has them in stock 655-R10-E1Y4-V2.5K
http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid= 214416&e_categoryid=155&e_pcodeid=65500

They solved my relay problems.

In the Drake TR-4 (no "C") and the TR-3,
the same relay will replace to
cheap white piece of junk Drake supplied,
though it must be soldered in.

P.S. "Hanging" relay is often a bad 6EV7.