What's going on here with my SMP GMT?

[EMM]

Have a rep SMP GMT (the black one) with an ETA 2836. Suddenly, when it's at the second stop, the GMT hand will only turn for a little while, then the stem will feel like the gears aren't meshing - not really grinding, almost like the feel of winding a 6497. Then it will move a click or two, and then stop again. Date (turning the opposite way) works fine.

So I replaced the entire movement, including the GMT wheel, with a new 2836 (was easier than fixing it). Same problem. No change whatsoever.

Doesn't seem like it could be the keyless because it was replaced when the movement was switched out. What's causing this?

Thanks

[photon]

Is this a common problem? Unlike 2893, this is not a natural born GMT mvt and I always wonder how reliable they are.

[FxrAndy]

do you have a friction washer between the GMT wheel and the dial? it may be that the gmt wheel gears are not meshing well if the gmt wheel is not held down or the dial may not be central casusing the gMT wheel to bind on the dial center hole and causing the gears to slip. At this point i would be checking this as a gear jumping will cause bits to wear off and cause a stopage or damage to the movement.

[EMM]

I can't see anything wrong with either movement. I think it's time to enlist the smith. Frustrating.

[FxrAndy]

Put the gmt wheel on the movement with out the dial and try it that way and see what happens that will rule out the movement if it is fine then and will indicate something out side the movement causing the problem

it cauld also be the slipping clutch wheel for the GMT?