CHART OF COMMON DIFFICULTIES SECTION 4
R. Commutator has unsymmetrical burn marks
	Possible Causes	Remedies
10	Oil or dirt on common commutator or slipring	Clean
14	Mica proud	Recess mica or use a more abrasive grade
15	High or low commutator segments	Tighten, turn or regrind
16	Commutator too loose	Tighten, use new mica and turn
17	Solderings interrupted	Resolder tags
18	Commutator or slipring excentric	Turning and grinding at near rated speed
20	Spring pressure too low	Adjust to brush grade
22	Spring pressure unequal	Adjust spring pressure uniformly
24	Brush flexible connection faulty	Replace by a new brush with good connection
29	Radial brush holders not in correct position	Adjust holder to radial position, distance from commutator 2-3mm
30	Reaction type holder mounted trailing	Reverse holders or direction of rotation
31	Brush sticking	Check brush size - remove burns and dust
34	Brush holder mounted too far from commutator or slipring	Adjust holder to be 2mm from commutator
38	Humidity too high	Enclose machine or draw cooling air from humidity object
39	Dusty atmosphere	Remove cause, install filter