No need to be sorry! First of all, as you probably figured out, I meant to say I thought the break was in the trace between pins 15 and 16 of the 74165. Im on the other side of the pond and it was way past my bedtime!
I'm not the greatest craftsman when it comes to yielding a solider iron, but I've been involved with electronics most of my life thus have some experience. The connections were all good with no bridges, cold joints, over or under soldiering. While I reflowed the contacts in question, none of the pads were overly cooked and damaged. I felt I checked my work and the schematic about 1000 times before I applied the jumper wire fix. Again, I could occasionally get the synth to boot up in its normal mode as opposed to the boot loader screen. At first I thought this was because I hadn't seated the chips properly, but it would only boot up right after my pressing or somehow slightly flexing the board and won't boot right on subsequent tries. That's when I really started suspecting a crack in a trace. Then, when I found that just the application of my finger around the 74165s and resistor network while the synth was unplugged was enough 'stimulus' (charge or discharge of what ever small voltages were there at the time) to consistently allow the synth to boot in the right menu (but still w/o button or encoder functionality), I became convinced there was an open in the curcuit somewhere and I began the steps to find and fix it.
BTW, the forum topic where mmarsh had no button functionality really helped me narrow the problem down. Not only because of how it was related to my problem, but because I figured if someone like him could resolve his problems to go on and create fantastic sounding music and demos with the Preen, than maybe there was hope for some poor soul like me!