On 10/15/2015 2:52 PM, DManzaluni wrote:

How will you KNOW that the "replacement unit" contains the desired "fix"?
I.e., does the part number change to reflect the fix? Or, do you also
need to know a *revision/version" number??

Because mine is so way off that pretty much anything would be an
improvement! My grub came out so undercooked that it was ruined and after I
changed the thermostatr itself, the temp now wavers from 50 degrees too low
to 200 degrees too high.

So, are you convinced that your unit is *defective*? (i.e., "in need
of repair") Or, do you just think this a bad design?

Curiously I was hanging out on some far corner of the internet and came
across a way of resetting the gauge to make it up to five or ten degrees
more accurate. But nothing like the wavering like I am experiencing.

Accuracy is a different issue. You can have *excellent* control
(i.e., maintains a temperature "dead on") and poor accuracy
(i.e., maintains the *wrong* temperature dead on!).

There will always be some hysteresis in the controller -- it's just
too impractical to come up with a critically damped system.

BTW There was a mistake in the OP: The unit is a PGB918sem3ss and GE says
that the part is and has always been a wb27k10176

So, there is no way to distinguish between a "new controller unit"
and a "not new controller unit"?

Have you observed the controllers actions in detail? I.e., can you tell
when the heating element is on (by glow or some other indication) and
correlate that with the observed temperature (via "oven thermometer")
to see that it is at least *trying* to function properly?

I.e., if the setpoint is 350 and you see the heating element turning OFF
when the oven gets to 250, that's suspicious. Likewise, if it stays ON
when the temperature reaches 450!

It's hard to say whether your problem is in the heating element, sensor
or controller. Until you can identify some *actual* behaviors.

There have been appliances with known design flaws (I can recall a refrigerator
that was notoriously warmer than the controls *thought*).

You can also look for an assembly drawing to give you an idea as to where
the actual sensor may be located. At the very least, you can then look
around to see if something is impeding it's "access" to the oven's actual
temperature, broken wire/capillary tube, etc.