I have a old GE drop in range/oven jm931r1wh.
The oven only works at low temperature up to 250 on the rotary selection switch which has warm, 150-450 and broil - 9 positions.
Note: oven also works on the broil selection on the same switch. the switch GE part number is wb22x53 (not a thermostat type switch).
also marked asr5177-10A

Is this switch the actual problem, or could it be something else (wires or thermostat type part?)? I'm hesitant to buy this switch for $90 until I have more certainty that it is the most likely cause.....

I don't have a schematic or know how this wb22x53 9 position rotary switch can be tested to see if it's causing the problem. it has terminals J,L,L1,L2,M,N,P,T1,W,Y. if I can have some idea of how it connects internally, I can test continuity with my DMM before I order it.

can someone suggest other diagnostics if this isn't a common problem with known solution? thanks.

(note: it is NOT a problem with the knob being on backwards)

as I mentioned directly in my original posting. bake works at the switch positions up to 250. broil works also.

yes. when set to 300 there is no heat and the oven on light goes off.
at 250 the oven is heated and the oven on light is on.

similarly at broil oven is heated......

the plate reads:
J M931R1WH/10.7

there is a space between the J and M, which I cannot tell if there was another letter/digit originally.

this is a GE 27" electric drop in range......

I gather the WH stands for white model since this range/oven is white......