I'm trying to figure out if I can change the 250k pot to a 200k pot since they're available on Tayda. It looks like it should be okay but I thought I'd ask here first.
If you don't have the 250k and have a 500k, install the bigger-value trimmer and solder a 500k resistor across lugs 1 & 3, that'll give you the needed 250k.