[Wavetek 75] Replacement part for main dial/Service Manual?

[Hoi Wong]

I have a Wavetek 75 Arbitrary Waveform Generator (AWG) but the main dial
(potentiometer) is (mechanically) broken. Does anybody know what part# do I
need to replace the potentiometer?

If somebody can send me a copy of the service manual(mainly to look up that
part number), it'd be great too!

Thanks.

Cheers,
Hoi