Battery/motor surge ?

[TacoCrawler]

Have a SCX-10
Stock RTR electronics (newer version)
plus castle 10a BEC set at 6v
Runs using 3s LiPo + Axial 55T mtr.
Stk spur with 18t pinion.

Problem is...

When crawling at very slow speeds the mtr will sometimes intermittently surge or possibly glitch.

It is random... and does not occur with any measurable consistency.
It does not affect the steering servo. (glitch)
Nor does it run throttle forward or out of control.
Just a slight surge.
Normally not any real issue...
except when stalled and trying to maneuver a critical ledge or tight spot.

Randomly it will surge just enough to fubar my chosen line.

Any idea what might be causing this ?

I don't think it was an issue when it was new...
Didn't notice it when running a 20t pinion.

is it possible to be geared too low when using 3s LiPo's ?
maybe the motor is dirty or contaminated somewhat ?

Thought I'd inquire before attempting any changes.

Thanks if you might have any info that may be of help.

[Charlie-III]

How old is the rig & motor? It's possible the motor is due for some loving especially if it gets run in water or dirt/mud that gets inside.

[TacoCrawler]

maybe 15 runs or so on this mtr.
The SCX-10 itself is only 6 months old.
Never submerged... tho' I did splash about in some water.
Possibly it picked up some contaminants.

Yeah... I'll clean the motor and see if any change occurs.

I just ran a 2100 3s LiPo thru it and only one surge (glitch).
( ^ mtr. not cleaned yet)

It seemed to surge when declining a rock.
The drag brake is set at 100% (not sure if that could of issue ?)

Only when transcending, from drag brake stall or idle (neutral) throttle,
to forward throttle does the slight glitch or surge occur. (and only once per incident)

weird

hopefully cleaning the motor might resolve this

^ thanks for your input