This Vox Continental had a problem with the Sawtooth Mix drawbar.  It had to be wiggled a certain way to get the sawtooth tones to turn on.

We tracked down a loose solder lug but the circuitry was hidden by a wooden support.  To see what was going on, we took out the drawbar assembly.

To do this, first pull or pry out the wire staple shown here.  It holds down many of the wires going to the drawbars.  Pulling it out gives the wires needed slack.

Some wires have no slack and must be unsoldered.  First, unsolder the wire end shown in the photo.  The other end of this wire connects, coincidentally, to the loose solder lug.

Then unsolder four more wires leading to the drawbar assembly.  The connections are circled in this photo.

Three of the wires are black and one is white.

Now you can detach the assembly by removing the four screws circled here.

Here you see four of the wires you'll have to resolder when reinstalling the drawbars.

The drawbar assembly is now detached and positioned on the workbench.

The problematic, sawtooth mix drawbar is the uppermost drawbar in this photo.

Here you see the drawbar mechanism.

A sliding contact connects an output terminal to one of nine input terminals.

A resistor ladder fixes the signal level at each of the input terminals. 

Our loose solder lug is the output terminal of the sawtooth mix drawbar.

The spinning lug broke a circuit foil, which would reconnect intermittently (right).

We used MEK to clean the solder lug and the circuit foil, then built up a solder bridge across the crack.