i recently got an engine and the valves weren't working so i opend up the case and saw that that the cam and governor gears were ruined. how do i replace the gears? its a craftsmen 5hp tecumseh weed trimmer.
engine model: 143.985012
engine family:STP185U1G1RA

You cannot replace just the gears, you will need to replace the whole camshaft and governor gear.

Camshaft part #37460
Governor Gear #30591

Keep in mind something has to cause damage to the gears so you may end up replacing more parts in the long run.

how do i remove the governor gear?

Back up one page, look at the top of forum, says "HELPFUL LINKS", theres a bunch of manuals in there.