Sanity check on diagnosis - glow plug relay

[0ilburner]

Hi all, I beleive I’m facing a failed glow plug relay, but wanted to make sure that I’m not missing anything. Car is a 1982 300d.

This morning I went to start the car and I get no GP lamp, and I cannot hear the relay clicking. Car starts but have to crank it for 10 seconds or so before it sputters to life. Steps I’ve taken -

I checked resistance of GPs, all are between .56 and .63 ohms.
Checked fuse in relay, looks good although it appears someone stacked two 80A relays together on it. Slight melting of the plastic around one post on the relay. Removed one fuse, cleaned contacts and reinstalled one fuse. Checked all contacts on the outside of the relay and cleaned them, corrosion minimal. I removed the relay and took it apart to check for corrosion, everything appears very clean with no corrosion. Date on the circuit board is from 1981 so I assume this is the original relay. When testing the wiring on the 4 wire plug I get power to the wire going to the 15 terminal (red with black stripe) when the key is in the GP/run position. No power to GPs, obviously.

Seems to me that this relay is bad. Did I miss anything?

Is it bad to crank the car for extended time to start it until I get my hands