Editing Atari 1020 Maintenance Guide (section)

== Motor pinion gears ==

The small nylon gears on the shafts of the carriage and paper feed motors shrink with age and split. A cracked paper-feed gear stops the plotter drawing accurate vertical lines, and a cracked carriage gear stops the pens moving back and forth; one new-in-box 1020 had both gears cracked.<ref name="ap1020">Jason H. Moore, "Repair an Atari 1020 Printer (30-60 mins)", ''Atari Projects'', 25 August 2018. [https://atariprojects.org/2018/08/25/repair-an-atari-1020-printer-30-60-mins/ atariprojects.org]. Community repair write-up.</ref><ref name="tandy" />

{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+'''ALPS plotter motor pinion gear (Tandy CGP-115 wiki)'''
! Teeth !! Module !! Bore !! Length
|-
| 13 || 0.25 || 1.5 mm || 4.5 mm
|}

Replacements are machined brass or 3D printed.<ref name="tandy" /> On the 1020 the paper-feed pinion is the smallest of the three gears on the right; it slides off the shaft and the new one slides on.<ref name="ap1020" /> When pressing on a brass gear, support the motor shaft with a vice with plastic jaws, and keep metal jaws away from the rear end of the shaft, which sits close to the bearing and deforms easily.<ref name="tandy" />

Atari's motor removal, if needed: lift off the motor cover with a flat screwdriver, unhook the paper holding roller support plate spring, remove the screw holding the motor, prise the motor out without bending the frame, desolder the jumper between the two motor boards, and desolder the reed switch wires (yellow and grey, carriage motor) or the electromagnet wires (red and black, paper feed motor). On refitting, check that the gears mesh and that the harness is threaded as before.<ref name="fsm" /> When removing the print head idle gear, move the bobbin gear aside without removing it, and do not cross or unwind its wire.<ref name="fsm" />