On the RF board (the lower one with the R2000 in the normal, upright position) the jumper and connections can easily be found by looking straight back from the AGC/NB/DIMMER switches. The jumper is a white wire, and the positions are labeled "FOR SSB, AM FREE SCAN" and "FOR SSB, AM BUSY SCAN".  In the "BUSY" position, any time a signal, or noise, breaks (opens) the squelch, the radio will stop scanning.  When the signal (or noise) disappears, scanning will resume.  In the "FREE" position the radio will not stop scanning regardless of the squelch state.  This works in either the memory scan mode, or "Program Scan" mode (searches between freqs programmed in M9 and M0).

This is an easy and safe mod, but I never found much use for it.  Now if it was a Voice Squelch instead of an RF level squelch it would be great.  The PCR1000 receiver that I used for a few days had VSC (voice squelch) that worked better than I expected.  It was nice to start the radio scanning and only have it stop on a voice signal.  Other than the VSC feature, the PCR1000 was not a great SW receiver.