The yoke looks like it has been contacting the reverse clutch disc, which it should not do.
So I suspect that the clutch disc thrust bearing, which the yoke clamps around, is cactus.
That's part No. 7 [Greenfield P/No GT855] in the E2000MK216-32 Illustrated Parts List, which you can download from the 'Ride On Mower Information' section over at
https://www.outdoorking-forum.com.au/forum/ubbthreads.php?ubb=postlist&Board=75&page=1 The bad news is, that it's a major job to replace this bearing - the clutch shaft has to come out. If the bearing isn't intact enough to get the type number off it, you'll have to buy it as a genuine part. It won't be a standard radial ball bearing, due to the thrust loads imposed on it.
Plan to check the clutch disc cork facing thicknesses while it's apart too, and replace these if warranted. They are a relatively cheap component, but there's a lot of work in getting at them.
