I bought a Mad Dog stereo flanger a while back, and (like most cheap gear) it messed up, doesn't flange anymore, if I want it to flange I have to MANUALLY turn the "DEPTH" knob up and then back down, then up, so on.

But I was wondering if there was anyway I could use some of the stuff inside the pedal and make a simple Volume changing pedal, not an expression pedal, but like I press it and it's like 100% volume, press it again for something like 75% of course with a knob to choose the secondary volume.

Would I need to purchase any other parts like a circuit board or anything? If you need to know anything else about it, let me know.
Well I've already come up with something that I think would work, not tested yet, but once I get the parts together and see if it works, Ill let you know if it does and how to build your own. I guess Ill just buy the parts new, there not that high I'm estimating less than $20 for all new parts
Plan A
First check the soldering on the speed knob!!

Plan B
Use an external expression pedal to change the depth.

What you need to do is buy an old Wah wah pedal enclosure, and replace the pot in it with this depth one or buy a new one with same ohmage value. If you want to add a jack... make another hole in the box. Then, wire the two leads to the two lugs on a mono jack.

then on your male jack, wire two leads to the two bits. easy peasy.