Parasound HCA-1200

[Rod]

I have four HCA-1200's Two amps work great the other two are doing similar things. One clicks once and stays in stand by never turns on. The other when I plug it in and turn on it takes about 30 seconds to turn on, the longer I leave it plugged in the faster it will turn on. My question is can someone tell me how to set all the adjustments back to factory setting? Like input offset voltage. DC bias and whatever else that could have been adjusted. I noticed when I tested them all with the same input volume level they all had allot different output volume. Also please tell me where to test these measurements I have a schematic. I read some old threads on this subject and John Curl said to check input offset voltage but im not sure how to check it. I apologize if my lingo is not 100% correct. New at board level.

Thanks Rodney

If I can help anyone with installation tips that is my strength's would love to help for some board level help.