Motor height is done both with shims and the screw on the bottom of the motor cage (it's a very tiny allen key central to the motor shaft on the cage).
Trouble is you need to correct the shimming before you can set the height.
Fortunately it's a caged motor but you will have to open the gearbox again.
My advice is send the gearbox to someone that knows what there doing. Have them service and shim the gearbox.
If you want to do it yourself then you will need to order some proper shims.
https://www.ak2m4.co.uk/internal-parts/bushings-shims/shs-ra-shim-set
Order 2 sets. So you have plenty of spares. You will find that you get a selection of 3 sizes and there all thinner than the "shims" that gearbox has in it.
Octagon: 0.1mm x 9pcs
Circle: 0.15mm x 9pcs
Red Circle: 0.2mm x 9pcs
To set the pinion to bevel gear. You need to use a system of trial and improvement.
Put in the bevel gear with no shims onto the upper shell. Drop on the motor cage. Wind the motor in till it looks right over the gear. Remove the cage add shims to bring the gear up to the pinion. Test again and move the motor. Once you have the perfect mesh on the pinion and bevel gear that is the motor height and bevel adjusted.
You then remove the motor and shim the bottom side of the bevel gear so it has no side to side movement, but is still able to spin completely freely. Put the bevel gear shims in a safe spot.
You then do the same with the spur gear. But this time you will drop in the spur, then the bevel gear with the shims on the lower gearbox half. Shim up the spur so it has full engagement on the bevel gear, Then drop on the upper half and shim the gear to the shells so it has no side to side movement but still moves freely.
You then do the same thing to the sector gear. Start with the lower shell and set it to the spur gear. The sector gear wants to ride as low as possible to the lower gearbox half, without binding on the spur and COL. Once that's right you need to set the upper shimming on the gear to the upper shell. It wants to have no side to side movement but still move freely.
Once all of those gears are set you need to build the gearbox without the cylinder, piston and tappet plate. Check all the gears spin well and have no side to side movement.
Then rebuild it again with the tappet plate added. Check the tappet plate doesn't stop or slow the gears.
Then rebuild it again with the piston and cylinder.
If you don't understand that..... Send the gearbox out to a tech for a proper service and shim.
