Here is what I did. I have tweaked lots of component values to my taste. It is not really a re-design since I followed much of the original design.

First, the diode did not really make a difference except reduce the depth. I tried it with 2N5089's and it did not tick. Trying different trannies, I stumbled on some that ticked a lot. The bc414B was the less noisy of all but I think it may be hard to find. So the 2N5089 is the best choice for most of us. In that case note that you must use a 330k resistor instead of 100k where the speed pot is connected.
Another thing I noticed and that is valid for the valvecaster too is about pin 4 and 5. Notice that I have reversed them (gnd on 5 and V+ on 4). It sounds less harsh like that, to my ears anyways

.
The original vibracaster lacked a bit of fast rates and "deep" depth. Using the values in my mods now make it possible to have really fast rates (think about the tremolo in Pink Floyd's Money) and setting the depth at maximum really chops the sound. Anyways, you may want to try the mods, it does not take much time. Tell me if you like it.

Again, thanks for your hard work on this project! I hope my contribution is worth it.

John