I don't think we have ever put any parts in any of the ones we owned other then hoses, fittings, and o-ring packs. 

Something to look at is the face where the steering arm bolts on. We've fought with the bolts breaking for years.  I finally started welding it at the beginning of every season and it hasn't broken (off) yet.   It still tends to be cracked by the end of the season, but at least the bolts don't break.