Yup that's the screw/drain.
.The fill/ vent screws are just that.
You fill from one and let it vent out the other, I fill from both holes till oil comes out both.
Use Mercury drain plug washers.45176 Merc part#
The OEM Force/ Chrysler are a plastic crush ring that is marginal at best and not re-usable.
Mercs can be used again and again.(see my boats name
)
Drop the lower and remove the pump and check the drive shaft for side to side movement.
The prop: Hook the hose to the lower and start it and put it in gear and see if the prop wobbles??
Yes? Then remove the prop and start again and check the prop shaft for wobble.
Don't buy a prop unless you know for sure what size. Guessing what someone else has isn't good.
A 125 on a 17 would probably be a 19p maybe even a 21p. A 15p would be for a heavier bigger boat. But I'm guessing??
Not sure how long this had been going on, was changing lube, greasing the PS I reinstalled the prop and just happened to spin it.
Big wobble. Under power not a bit of vibration, no nicks or dings.
It would have eventually wore the bearings in the carrier and caused failure.
Had a spare with a quarter size nick and it runs good and no vibration from the nick.
Remove the cowl when starting and watch the flywheel.
See if it runs true and no wobble.
Bought a "running great" 125.
Got it running and it almost shook off the stand.
The flywheel key had slipped, not sheared and the FW flopped as it turned.
New key and re-torqued.
