This page might also be interesting for you:
Click me, but not too hard ;-))) (http://www.moogarchives.com/moogth2.htm)
If there will be no success at Moogs, you should take the diameter of the pitch rod support and try to find a fitting copper tube. Start with a length of about 60cm (24 inches) and verify that you can go up enough in pitch. If pitch seems to be limited in the higher tones, shorten the rod inch by inch, verifying that the playing range towards the low tones doesn't get too limited which will be the case if the rod is too short.
Take your time and make use of the pitch adjust knob in order to learn about this intrument's behaviour.
If you found the correct length, you may replace the copper tube by a more beautiful material (i.e. chromed copper tube) with the same dimensions.