Bunton BZT 2190 Relay issue

My Bunton BZT 2190 has 3 relays in a block under the seat. A few years ago, after starting the engine, as soon as I release the parking break, the engine died. Unable to find a readable schematic, I began to trouble shoot by just trying things. I discovered that by removing the center of those 3 relays, the problem goes away.
 
I know the relay itself is not bad. I can swap all of the relays to the other locations, everything still works, unless any of the relays is in the center position. I have been mowing with it like this for several years.
 
Just now, my son called, he has an identical mower with 500 less hours than mine. I have about 950 hours on mine. He suddenly has the same problem. I suggested he remove that relay to see what happens. Now his works.
 
Does anyone have an explanation what the real problem might be. The unreadable, to me anyway, diagram on this site shows this as a "delay relay", but I am not able figure what it actually does.
 
Thanks,
 
John