I looked at the schematic again to refresh my memory. Complicated beast. It is a shame that these fine tuners can not be fixed just because of one or more important components. Lots of special comps, with no stock, designed for the garbage can.
Like I said before, what have you tested to determine that it is the vfd, (fl1)? I would hope you used a scope,monitored the drivers,ic3,4,check filament drive etc to come to this conclusion.
Lots of fun to adapt another vfd to this one, trying to match all the pins, fun wow.
I like picking up dead tuners on ebay
hopefully for you, it does not come down to this. In time, more will die, hopefully because of other issues and make a spare available. I hate vfds for this reason, like real expensive obsolete incandescent lamps
I have a crown fm1 that has a dead controller, real simple compared to a L-1000T. tl072 ;-)
I got it going again with a heli-pot to adj the varactors, added a center tune meter on the ca3189 afc ckt and today I got a freq display running = yea, but it is a bit of work just to get here, designing a new pll tuner, code display is a much bigger job.
So I can offer you ATtiny2313 code to display the frequency on a cheap lcd
What pre-scaler is used? I can't find it now, sch are a bit hard to follow, need to print out to follow better.
Good luck