[Milsurplus] BC-348 Backlash Suggestions

[David Stinson]

Been reviving a BC-348 for a friend.   
It had a "doofuss-try" I hadn't seen before- 
someone rotated the bandswitches 180 degrees.  
Didn't know you could even do that.

After this and lots of other work, it's playing well
and is one of the best sounding 348s I've ever done. 
Even the crystal filter works well.
One common problem remains- tuning backlash.

The three major contributors to backlash in a 348 
are the tuning capacitor gear, the worm wheel and
the worm shaft.  Here is a photo:

http://home.netcom.com/~arc5/348gears.jpg

First, make sure all the gears are clean and lubed.
Put some drops of GOOD penetrating oil 
on the edges of each gear and let them sit.
Do this until the two halves of the gears 
move freely.   You can test this with a small
screwdriver inserted between two edge teeth.
Mesh the teeth and they should spring back.

The gear on the end of the cap is not too tough
and that's good, since it's usually the big baddie.
Just takes patience and practice.  Close the cap all 
the way and make sure this coincides with the end
stop on the tuning knob.  Loosen the two screws on
the gear end, but don't remove them.  You want to be 
able to disengage the gear from the pinion, but just barely.
This is best done at a 45-degree angle toward the front.
I use a pair of hemostats to engage both sides of the 
gear and well-compress the spring.  
Then, making sure the tuning knob is still on the stop 
and the capacitor is still fully meshed,  
re-engage the gear and tighten the cap back down.

The parts where I could use suggestions.
The worm gear wheel also needs to be retensioned, 
but the assembly is pinned together and the ends 
of the pins "boogered-up" so you can't drive them out
without damaging the whole assembly.

I can't disengage the worm gear wheel to retension it 
like the cap gear, nor can I remove the worm gear shaft, 
as it is also pinned.
In the past, I've used hemostats to removed one of 
the worm wheel springs, stretch it out, try to put it back, 
cursed at the 27th try, then watched the spring 
"sproing-ing-ing" off into oblivion,
found another spring in the junkbox, 
stretched it too much so that, once I did get it on,
it stuck -out the sides of the gear etc. etc.

And then there's the worm gear shaft- 
this problem is nasty and is also common on later production 348s.   
The worm shaft slops "in and out" towards the back and front.
Common symptom is "wibble-wobble" while tuning
that is most pronouced on the higher bands.
The shaft has a wimpy leaf spring under the worm
and a felt pad under the tuning knob that help some,
but it's no cure.
I cannot remove the worm to add a washer or bearings
under it.  Only someone with an advanced machine shop 
should attempt it since you will absolutely wreck the thing 
if you try to hammer and whack the pins out.
So I'm looking for suggestions on how to address
the slop in these two gears.

How about a couple of snap-rings under the worm shaft?

TNX ES 73 DE Dave AB5S