Hi,
They have said on here before that the spec in the service manual for the depth of the governor gear oil seal was made when the seals were thicker, so it may need adjusting for modern thinner oil seals.
If needed, you might be able to change the position of the seal slightly if the governor gear is worn where the seal was before, to make it run on an unworn place on the gear surface.
I think the manual says leave the front cover bolts loose some, until after you put the front pulley on, so the oil seal can be centered on the pulley seal surface.
Below are pics from TM Tractor, of the governor gear and the idler gear.
The timing mark on the governor gear is on the edge of the tooth, on the left of the pic.
The timing mark for the governor gear is on the rear side of the idler gear. Look closely. It is on the right in the pic of the gear below. It should be shown in the manual.