I have never had to do a speed control adjustment.
But it really is not that hard.
Put the belts on then with the Engine running put the F-N-R lever on the N
Start at first gear and one at a time shift to high Gear then back down to first.
This will help set the belts.
To make sure I understand: I start in 1st gear, shift to 7th gear then back to 1st. Then shift to 2nd gear, up to 7th then back to 1st? Then shift to 3rd gear, up to 7th then back to 1st and so on through all 7 gears?