Mariner 20hp washers or o rings on gearbox drain / fill plugs?

[fender22]

Was replacing the gear oil today and noticed only one of the plugs had a washer on it. Thought it might have dropped in the dish I had underneath but wasn't there.

Going to pick some new ones up tomorrow but wondering is it just a fibre washer or should there be an o ring on there too?

[Spaniard_King]

No O-rings on that model only fibre washers. Buy genuine ones a couple of bucks might save you a gearbox. Also have a good look as the washers can be hard to see jammed up inside the plug cavity