Modification to increase the 6MHz subcarrier sound level and change frequency
 

We've found that the -30dBc sound subcarrier level isn't quite enough to open the squelch on some repeaters. This modification is tricky but it will increase the subcarrier level to about -20dBc.

Open up the transmitter can. Solder a 10n capacitor (either leaded or surface-mount) across the resistor circled in RED in the picture. Be careful - there's very little space to play with in there!

You can also increase the 6.5MHz sound subcarrier level by soldering another 10n cap across the resistor to the left of the one indicated with the red circle. We believe (but have not confirmed) that you can disable the 6.5MHz sound oscillator by removing the resistor to the left of the one indicated with the red circle, or snipping one lead of the left-hand 100 ohm resistor (just above the left-hand variable inductor).

To change the frequency of the soundcarriers above 6,5 MHz, change the capacitors circled in yellow in the picture. 
Use 8,2 Pf for 7,02 and 7,20 MHz.