[Test-Equipment] AVCOM PSA-65C questions

[Don Moman VE6JY]

A recently acquired PSA-65C (no manual, of course) has some "issues",
but seems to work well when powered thru the ext DC jack.  The internal
power supply seems to not provide enough power, but I haven't looked
into that yet.  I also believe it has a serial port, but seeing none on
the rear panel, it either must be an option or wired into the front DIN
plug??
 
I believe service info on this stuff is very scarce, but if anyone has
any tips, I'd appreciate them.
 
My main question is about the LCD readout for the center freq,
start/stop and span functions.  While it appears to be quite accurate,
it takes a LONG time to update after you turn the knob or change any
settings.  Like 30 seconds or more.  The lock led flashes 3 times, then
stays solid after you stop tuning, then eventually the display catches
up.  Surely this isn't normal?   Again, any suggestions appreciated.
 
Thanks, Don
VE6JY