Sanpera I amp pedal does not work consistently with peavey 30w amplifier

For thwe best info, contact Peavey Customer Service. Here's the link-
peavey com

your best bet is to contact Peavey directly. they can provide you with the manual and discuss your application. Here is teir contact page-
Peavey com

COntact Peavey for the manual and suggestions as to setup. Here's their link
Peavey com

Contact Peavey toll free at 877-732-8391 or by email at [email protected],

Either the cord is bad or more likely the jack needs to be resoldered or replaced.

Should check the AC adapter if using one. Have you ever used one on it? Was it original or generic? Polarity may be wrong or not strong enough, unit may have damaged. If you answered these questions, I may can help you. you can find your manual here:

http://www.musicmarket.sk/files/product/1/10/488/data/peavey-sanpera-ii-footswitch-player-handbook.pdf

should be either on the side or the back ( where the cut away part it )

That would mean fully depressing pedal forward.

The pedal is attached to a rotary reostat (volume control) - usually geared directly or connected with a belt. Make sure the connections are OK - it might have come disconnected or the wires may be broken - check the cables in the pedal and also the pc board they're connected to. If not. it may be the reostat that needs replacing

Have you tried replacing the cable that goes between the sanpera and the Vypr 30? It could be as simple as a bad cable.
Good Luck