I had a 33609 through the shop, some years ago...at least two visits. Sorry I can't recall what the complaint was but IIRC, all issues turned out to be soldering related. I think the main issue was a joint on a six pin, T0-18 type transistor. If you picture a perfect solder joint as a volcano, with the upper slopes clinging to the lead, the bad joint was like a volcano were the very top of the rim had collapsed. So, at first glance it was a nice conical joint, except that the part where the solder is meant to wick up the lead had shrunk away from the lead, leaving a gap.