Editing Apple Desktop Bus Mouse (section)

==== Erratic Cursor Movement ====
'''Symptoms:''' Jumpy, inconsistent, or drifting cursor movement

'''Root Causes & Solutions:'''
# '''Dirty encoder wheels''' (Most common)
#* Remove ball and inspect encoder wheels for dust/debris
#* Clean wheels with cotton swab and 90%+ isopropyl alcohol
#* Use compressed air to clear encoder slots
#* Ensure LED/phototransistor pairs are clean

# '''Worn ball surface'''
#* Check for flat spots or uneven wear
#* Clean ball with isopropyl alcohol
#* Replace if severely worn (19mm rubber-coated steel ball)

# '''Encoder wheel damage'''
#* Inspect for broken or bent encoder wheel teeth
#* Check encoder shaft for excessive play
#* Replacement requires donor mouse or compatible encoder assembly

# '''Controller chip issues'''
#* Test with known-good ADB system
#* Check for proper +5V supply at controller
#* Controller replacement requires exact matching part