I started a post and then forgot to copy in the rest. As I stated, I started working back from Section 6. Test point  is just before R740 In checking all 3 connections of this resistor I saw that the garbled signal was only seen on the side facing R741. Id visited this pot before two weeks ago, it cleared up after agitation, but came back. This time before attempting replacement, i hit it with deoxit and then worked it, no problems for several days since.