I need to install the fan shaft support on my 620 JD tractor. The shop manual cautions against messing with this at all. (My guess is that the gear alignment at the governor is affected). Too late, the support has been messed with. Now how do I reinstall it properly? There were some thin washers (shims) between the main case and the support, but not as many as indicated in the parts book. Any insights or tricks of the trade will be welcome. Thanks in advance.