I just finished restoring an early serial 2270 for a friend (s/n 2801). The bias on one channel would start at zero and climb to about 19mV over the period of an hour. I had originally replaced the bias transistors (H760 - each board) with ksc3503. Following the recommendation of an earlier thread, I tried a D669 and the problem was solved. I did not develop this solution. It was originally proposed by member ecluser in a thread titled "Marantz 2270 bias won't go below 15mV". The solution works because the 669 has a Vbe of .68 while the 3503 Vbe is .74 and this is enough difference to solve the problem. Many thanks to Glen (ecluser) for this solution. Please refer to his thread for a very thorough discussion. I have seen quite a bit of interest recently in the 2270 and thought this might be helpful to resurrect an excellent solution from the past. BTW, it's been my experience that the early 2270s take at least an hour to stabilize the bias.