I currently have a Hi-fi setup consisting of 1 x Sansui Integrated DC Servo Amplifier A-60, 2 x Memorex 505 Speakers.
Having problems with volume balance, from left and right channels with the balance nob in central position the right channel sounds quieter than the left channel but with the nob turned more to the right side its perfectly balanced ive played a test test tone through the amp and it has a Peak Power read out on the front, While the left channel for example is 50 Watts / 8 Ohms the Right channel will be showing 10 Watts / 8 Ohms and there is a noticeable power difference, also now and again very rarely the right channel will decide to turn itself off and only way to get it to play is to turn the amplifier off and on again. Not huge problems but it would be nice to know any information and what's causing this. Apart from these flaws its a amazing amplifier cant knock it warm sound and more than enough power even running 2 x Memorex 505 speakers each 120 watts power handling.
The problem could be in several areas of the amplifier. There's no way to tell without putting the amp on a test bench and going over it with a bt of logic to eliminate possible problem areas. The point to make is, if you have to ask where the problem might be, then you probably don't have the test gear, available parts or knowledge to make any repairs yourself. Poking around inside an amplifier can be dangerous and is not advised unless you are certain you won't kill yourself by touching the wrong part.
The amp needs to be serviced by a competent technician familiar with the old Sansui products. There aren't many of them left. Start by contacting Atlas Audio Repair (atlasaudiorepair.com/(412) 681-2092). You can also try AudioKarma's website. There might be someone there who is knowledgeable about a more local repair shop willing to take on vintage gear.