Vintage 70's Acoustic 330 Bass Guitar Concert Amp Head

According to what I have been able to find on the net the 330's were manufactured between 1978 to 1980. This is a power house. The output rating is 160 W RMS @ 4Ω, and 300 W RMS @ 2Ω. It has three (3) preamp 1/4" jack ins and three (3) preamp 1/4" jack outs as well as two (2) speaker outputs. The amp is in good condition overall, but the Master Volume & Reverb are not responding. All indicator lights power on but there is no change in volume or sound when using the Master Volume & Reverb. Both channels are working and there is plenty of power through both, but the amp will need some work to get it back to it's former glory. The pots & switching is scratchy & noisy and will need a good cleaning. There are 3 slider tabs missing on the EQ. The carrying strap is intact and the feet are all intact. The power cord is about 14 feet long and has an upgraded grounded plug. Check it out!