Samsung SXS RS2556ww ice maker issues

[Mr. Fix-It]

The icemaker on this fridge fills but does not eject the ice.
As a result the tray eventually fills and overflows with each
cycle. Pressing the test button on the unit it cycles properly
and dumps the ice. Does anyone know what would cause
this, the service manual is not very  clear on this, I'm
thinking the main board may be the problem but I'd
like to know how to verify this without just putting in
a new board and hoping it's the problem.

[JWWebster]

The ice maker has a thermistor page 21

[Mr. Fix-It]

According to the service manual the main board has to detect the
thermistor temp to activate the harvest cycle which is to twist the
tray to eject the ice, then relevel, then activate the water valve to
refill. If you push the test button on the icemaker it does these
functions correctly. In normal operation it does not eject the ice
(twist the tray) but does refill and eventually overflows so that
tells me the thermistor is ok or the fill part of the cycle would not
activate. The manual is pretty sketchy with schematics and info
on the icemaker.