Had a defective relay so I opened it up. Might be of interest or not.
First pic (top view) shows copper lead from #30 pin to solder terminal and just to the right of that is the attach point for the tensioning spring which keeps it in a normally open position with it's relationship to #30.Click to view attachment
Next pic shows side view of contact points. The pin on the left is #87 and the pin on the right is#87a. Notice the double contacts and that it is currently in contact with #87a. One contactor point above and one below with the plate contactor (which #30 is soldered to) in between, moving between these 2 points. I guess that would make it a double throw switch of sorts. In it's non-energized state #30 contacts #87a. When energized the electro magnet pulls the contactor plate down and away, breaking contact with#87a and connecting to #87. Click to view attachment
The 3rd pic is a side view of spring attach points and copper lead from #30 pin. Of the 3 front pins, the center pin is #30, the one to the right of it is the infamous "I ain't got no voltage here" #86 and of course the one on the left side is #86.Click to view attachment
One last thing. The #85 & #86 pin positions are flip flopped on the relay pictured on pg. 161 (in the Hayne's "Keep Trying Manual") from those pictured on pg's 147 and 154. Really?

I never opened one up. Nice pics... thanks.

I made a tool out of an old relay, by jumping the pins. Its good when you want to run your fuel pump, test circuits, etc.

I used to work for NCR and we had a proof machine that had maybe a hundred relays similar to that for what was called relay logic. The ones we had had about 4 sets of contacts though. That relay looks to be repairable. The contacts on most relays usually have a condenser or diode somewhere in the circuit to keep the contacts from arcing when they open. If they arc they will burn eventually. Like the points in a distributor have a condenser. When you clean points if you file them usually you remove a thin gold or silver coating that keeps them from oxidizing. The least destructive thing to use is a points file which is a really smooth abrasive file or a sheet of typing paper or say some 400 grit wet or dry paper. At lot of times a relay failure is the plug in connection gets dirty or corroded or the female receptacle connections get spread out from being unplugged and replugged too much in troubleshooting.

Yes, it is repairable. In fact it was cleaned prior to photo's and was proven. It was rusty and not able to move when energized. I suggest that moisture was able to enter via the slots in the pins themselves coupled with a long period of non-use.