DRO questions

I have a few DRO questions. I have a Teledyne Gurney PathfinderII on my
Bridgeport. The Y axis went belly up last week right in the middle of a
job. I thought that it was the scale since I had to re-engineer it to
get it going several months back. Burned out light -not available. No
parts available from TG. Very obsolete for some time I guess,they
couldn't even find used parts. I used a 5V grain of wheat bulb to get it
going.
Well, after tinkering with the scale for about 5 hours, I decided to
swap axis plugs at the DRO unit and, bingo, I was working on the wrong
piece. First question is: will the Kaluga/Mauch setup accept input from
these scales? In the event that I cannot repair the problem in my
Pathfinder. The linear scales are .0005 resolution optical.
Question #2 : I would like to go with the closed loop stepper system. My
motors are equipped with encoders( BEI probably 500 pulse). But has
anyone considered using linear scales in the closed loop system to deal
with back-lash? Or is that an impossible situation of playing catch-up?
Question # 3 : anyone have any Pathfinder parts?