We recently had a query about servicing intermittent Orchestron keys, and Robert typed up this guide, which I thought would be helpful to add to the blog:

The Model A is basically a modified Optigan® chassis in a different box.
Usually these don't have key contact problems.

The other models (Model B, Model C, Model D and their variants) have
"J-wires", which are gold plated wire contacts that are pushed against a
common bus rod by the keys. These models have key contact problems.

There are two things that should be done to eliminate flakey keys:
1. Replace all the capacitors on the keyboard PCB
2. Replace all the J-wires

The capacitors get leaky over time, causing a small DC current to flow
when you press a key, creating an audio thump. Even if yours doesn't thump
on every note, you'll be doing yourself a favor to replace them (you'll
have to remove the PCB anyway to remove the J-wires--next step). I
recommend using quality film capacitors, which will last forever. Make
sure the voltage rating is at least 25V (the bigger the voltage rating,
the larger the cap so don't go for too high of rating or you'll have a
problem fitting them on the PCB.)

The J-wires must be replaced. Don't try to clean-sand-polish them. It will
only be temporary and will give you grief later.

I buy J-wires from Carla Batman at Organ Service Corp:
P.O. Box 372
Marengo IN 47140
Email: carla@organservice.com
www.organservice.com

The J-wire part number is 999-036-00 (CONTACT, KEYBD LOOPED J-WIRE).

Email her to ask for current pricing (used to be around $1.50 per wire).
This is not a fulltime job for Carla, so it may take her a few days to get
back to you.

The J-wires from Organ Service Corp are not exactly the same as the
original Orchestron J-wires, but they are easily modified to work by
making two cuts:
1. The original wires are "J"-shaped; the new wires have a coiled-spring
bend. If you cut halfway up the first coil, you can get the wire into a
j-shape.
2. The new wires are too long, so the lengths need to be trimmed. I do
this as a last step after soldering them into the board so I can ensure
they are all trimmed to the same length (using the original wire lengths
as a guide).