Hi BenK,
Here is a couple of sites I have bought spares for Kirby/Tecumseh engines.
http://www.powerequipmentwarehouse.com/genuine-oem-tecumseh-parts-2
http://www.mfgsupply.com/garage/vehicleparts/parts/smallengine/tecumseh/h30/all/
Both great sites and the power equipment warehouse has exploded drawings with part numbers you will have to troll through.
The main issue is the pto oil seal but you will find it under part number 28540.