[ARC5] LM Cloudy Dial Window

[Richard Knoppow]

    I have had pretty good success polishing plastic with 
toothpaste. I was able to fix a field lens from a Rolleiflex this 
way. The Rollei lenses were made of celluloid and become cloudy 
if cleaned with Windex. I was able to salvage one by polishing 
with plain tooth paste. Also had some luck with CDs if not 
scratched too deeply.
    Unfortunately Celluloid, which can be either cellulose 
nitrate or acetate, is sensitive to moisture and can become 
cloudy or warp. Some will just disintegrate like the labels on 
Lionel J-36 bugs. No cure but to make a new one and replace the 
original.

On 2/5/2022 10:53 AM, William Cromwell wrote:
> Hi,
> 
> I have been working on an old LM-13. It suddenly stopped working 
> one fine day. I found a couple of electrical problems including a 
> tube socket and repaired successfully. Meanwhile the plastic 
> window over the coarse frequency dial is clouded up too much to 
> actually use. I see that the window and it's parts are riveted to 
> the front panel. The obvious thing would be drill out the rivets 
> and make a new plastic window with fiducial and then remount the 
> assembly with small screws. Lots of fussy work. Have to remove 
> the coarse dial drum for access. I have already made 'witness 
> marks' to get the drum back in place.
> 
> I could use an exacto knife to cut out the plastic window from 
> the outside. That would need an external bezel with the plastic 
> window fitted inside the opening and the bezel holding it in 
> place and glued to the outside of the front panel. Removal of the 
> dial drum not required. I care less about original appearance 
> than i care about useful function.
> 
> It might be possible to clean up the original plastic window with 
> the compounds that are sold for cleaning headlight assemblies on 
> our cars. I don't expect it to work but is the lest invasive and 
> easiest to try. If/when that fails I would get out the exacto 
> knife and try that route.As a last resort I would get out the 
> drill bits and use a hand tool to drill out what looks like soft 
> metal and take the long route.
> 
> I am thinking of adding an LED dial lamp inside behind that window.
> 
> I wonder what other LM owners have done about that window.
> 
> 73,
> 
> Bill  KU8H
> 

-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL