I bought a used Ampeg b4r a few weeks ago and I love this amp, but, the other day I noticed several things didn't work properly. the first problem I noticed was the texture switch, it made no change in tone what so ever. So I took the amp apart and looked at the schematic closely and noticed that the 1M OHM resister for the texture circuit was missing. It looked as if there never was a resistor soldered in. I thought this was strange so I soldered in the correct value resister and the texture button worked. Could Ampeg have missed and left it out? The other problem I'm having it the 15db pad has no attenuation at all. I haven't had a chance to really troubleshoot this problem But I did inspect the circuit board and all components are there and of the correct value. any ideas why the 15db jack doesn't attenuate the signal?