I also verified that there was continuity between the cathode of D513 and the drain of Q511, but there is no continuity between D510's cathode and the Q511 drain (which according to your schematic, there should be)...? There is continuity between the cathode pad of D510 and the inner pad of L513, so the solder on D510 cathode pad is good.
Just before I posted this update, I checked the continuity between the L513 pads (which are in series with the D510/D513 cathodes path):? nothing!? I reflowed both pads and now there is continuity between D510 and D513 cathodes and Q511 drain.? I performed a LPF sweep and now the 15/17m bands look correct!? Breakthrough!
However, the high SWR problem remains, though things do look better for the highest two bands.? See new SWR and LPF sweeps attached.? RF filter sweeps all peak between -3 and -7 dB.? Audio filter sweeps are all around -5 dB or so for USB and -50 dB or so for LSB, so those look good, too.
Spencer WD4AWD
