kz650 neutral switch o-ring/oil seal/crush-washer?

Hi all, I'm trying to figure out what is supposed to be behind the neutral switch on a 1980 kz650 F1 to hold the oil in. I've got a leak there, I can't access the bike right now to take it off and look to see what's under there, but I suspect there's a oil seal or an o-ring or a crush washer there. The neutral switch shows up on the 'Gear Change Drum & Forks' diagram on the kawasaki site ( www.kawasaki.com/Parts/PartsDiagram/143233/1980/KZ650-F1 ) but there's nothing else with it. Is there an oil seal there? if so, part number?
This parts company ( www.cmsnl.com/products/131511080-neutral...515002/#.VlpSr0bvaBY ) shows the switch being sold with a washer, which makes me think it may be a crush washer like the oil drain one - if that's the case, does anyone know the dimensions?

I looked at the diagrams for the neutral switch and the tranny cover it screws into, but I don't see a washer or seal. Nonetheless, there is a red washer there. Here's a picture of that area on my 1977 KZ650-C1. Notice the red washer behind the neutral switch. I've owned my bike since it was new and none of that stuff has ever been removed or changed, so what you see is how the switch came from the factory. I cannot find that red washer in the parts diagrams. The diagram of the tranny cover doesn't even show the hole for the neutral switch. Ed

The red washer is the seal. Same type on float valves and other places on the bikes.
Steve

Nobody has ever leaked there up til now, so unknown territory. Only reason it would leak is if someone fooled with the switch I suppose. I never gave mine a thought all these years. If it's a metal gasket or a paper gasket, I can't see any reason it would ever leak, but if it did, I would just put a little Yamabond 4 sealer on it and be done with it.

Or silicon would work.
Steve

The gear change drum & forks diagram for the 81 650-CSR shows a gasket, and according to the x-ref at Partzilla, a million Kawasakis use that gasket. The csr neutral switch has a different part number than the earlier 650s & I have no idea if the gasket fits the earlier switch. It probably does, but that's just a guess. The earlier switch probably included the gasket, hence no part number. ???

1981 KZ650-H1 CSR
92065-058 GASKET CHECK VALVE