As a very very very ROUGH guide......
Box open, no spring/cylinder/tappet plate etc....
Start with big middle or Spur gear & bevel gear....
bushings: require much less shims than bearings
thin shim under spur gear & few shims on top
bevel gear few shims underneath & thin shim on top
bearings - similar but will require say 2 thin or a medium shim under spur & on top of bevel - then a tiny bit more to take up "slack"
Sector is done last after those gears and shimmed as what is required - but after spur/bevel
The bevel gear is shimmed a tiny bit higher than a tiny bit too low - coz as motor is wound inwards it forces the bevel gear up
a bit - more so if bevel is too low being forced upwards to get a good "mesh" between motor/bevel
if bevel is way too low it is forced tight against bushing/bearing and really strains the motor and box.....
NB: please note this is a very very rough guide and please seek out a few videos on how to shim - watch a couple at least with good reviews/comments
I only put this rough crap description together to try and describe where I was going wrong on my first lot of gearbox tinkering......
It really was a bad set of guidelines I was following on a repair kit instruction that only after I googled and watched stuff I realised what bollox I was doing
you should check and really take your time in shimming and aim to get it as best as you really can, don't aim for perfect zero play shimming
a little isn't bad when holding box together by hand - but should test by tighten - NOT MEGA TIGHT the box up, coz when screwed up that
little play by hand halves itself when screwed up....
The way the gears lay/sit, a tiny gap as gears lay in box but don't cross etc.... - sounds simple but can take 6, 12 or more attempts
to acheive the best possible shimming results you can get or get within your own skill/patience/ability etc....
The better it is shimmed the longer it will last - fit the best possible bits in there but if they are just chucked in even a
crap box with pi$$ poor bits but properly assembled box will last longer
