EHX Soul Preacher - sudden volume drop

I've bought an Electro Harmonix Soul Preacher compressor, and have noticed repeatedly a sudden drop in volume while playing for a while.

I start out adjusting the gain so its the same volume switched on or switched off. When the volume drop happens, it's same volume when switched off, but lower volume when switched on.

Is that something I have to deal with with this kind of effect or is my compressor broken? I don't think I can live with that if it happens during play.

Have you ever had such a problem with any effect before and what did you do about it?

Thanks in advance for your help

[bongomania]

If it's something that only happens after you've been playing for a while, then it's malfunctioning. I've had similar things happen with other pedals; in one case it was a pot that went bad, in another case it was a single resistor with a bad solder joint.