Hi Gizmo, I have done a little research for you for the cutter sprocket....Unfortunately spare parts are very thin on the ground for the Imperial....I have found none listed anywhere.
Maybe the cutter sprocket that is fitted to the Morrison/Masport Olympic 500-600-660 may be the same diameter and pitch that is required....but I am only guessing. You may have to source one in New Zealand where they are manufactured in Hastings.
Re: the bottom knife blade, the engineer that does the spin-grind will be able to make one for you if necessary, or regrind yours if it is serviceable.
You should also take the sprocket to him and ask his advice...he may have a good idea or able to fabricate one.
As time goes on, these machines are going to be harder and harder to service, due to the lack of spare parts.
