Simpson Model 260 Series 5 Repair

I was at my mother's house last week and stumbled across several valuable items (?) and brought them back home.

• Simpson 260 Series 5 VOM
• Simpson 10mA analog panel meter new in box
• Minerva Stop Watch
• Two inexpensive plastic slide rules

The large slide rule is one I bought for high school physics and has my name scratched on it. I'm not sure where the other one came from.  I have a better Pickett slide rule I used in college.

The meters and stopwatch watch belonged to my father. They've been sitting in a box for the last 35 years and hidden in a closet.  The stopwatch seems to work fine.  I haven't tested the 10mA meter yet but it looks cool.

I had looked for the Simpson meter in the past because they were high-end meters back in the day but couldn't find it.  It isn't the one he used when I was a boy but I remember it in his shop after getting out of college.  Unfortunately, the batteries were left in it.  And it looks pretty crusty.  

I've removed the battery contacts in front and made a first pass at cleaning them by putting them in vinegar, rinsing in water, and spraying them with alcohol.  I lightly brushed the ones that are attached to wires with vinegar and sprayed them with alcohol.  There is corrosion crud scattered around and I've brushed that out with a soft toothbrush but everything still needs cleaning.  Note that there is visible corrosion on one of the PCB traces upper left.  There is still continuity across that trace but I'm worried about scrubbing on it and possibly lifting the trace off of the PCB.  There is a capacitor used for removing DC when measuring AC on the underside but it looks OK and I won't be using the meter for AC anyway. 

I won't know if the meter movement is still good until I can clean it up and put batteries back into it.  It takes 4 AA and 1 D battery.

I've found all the manuals and schematics and watched a couple of YouTube videos.  The Simpson 260 is an iconic and very well-known meter in the US so lots of information is available. This isn't the type of thing I normally work on so if you have thoughts on this kind of restoration please comment below.