Mikidymac: DI isn't carb

It's the most complex and expensive to repair 951
The impeller is located within the jet pump housing. It's what pushes water rearward, thus pushing the ski forward.
No, the carbon ring would impair movement, not the
engine. Without grip on the water, the engine would easily reach high rpm, you just wouldn't go anywhere.
At this point, and from photos, I'm not 100% sure I could diagnose a carbon ring issue, other than it leaking water. If you're going to remove all the stuff required to replace a carbon ring, you might as well just buy one, as it's around $20-30...
Testing a ski by running it on land is like testing a car by leaving it in park. It's possible, but you're not going to get much out of it...
To replace the carbon ring. and sorry I don't have pics, I get my skis ready next week, after the boat goes to the marina for summer and frees up some garage space!
I've never worked on an RX, but I've done work on
every other 951 ski and some 787s.
Remove seat.
Remove whatever is in the way of getting to the Power Take Off PTO (rear of engine) usually a grey or white cover attached with white plastic wing nuts on each side, and maybe a zip tie on the top.
DON'T loose any hardware, and please put things back correctly. I've sent many ski to it's grave because someone couldn't be bothered or used non-stainless hardware...
I think I found a video that will work:
I didn't watch it all through, but be sure remove the clip before you remove the jet pump. Else you won't be able to push the shaft in enough to get the clip out.
I don't know if the carbon ring is your issue, but if you back the ski into water on the trailer, and run it on the trailer, you should be able to see if water is entering via this area.