SMS is trained in the repair of all types of saildrive units. Both Volvo and Yanmar, our techs are factory trained. Many saildrive problems are caused by the mismatch of propellers or the lack of maintenance. The drive unit lubricant should be changed annually, or more frequently if the unit is used daily. Many saildrives allow the changing of oil without having to haul the boat.
Saildrives are made of aluminum and require regular maintenance to prevent excessive corrosion of the housings. This means that when you haul out you need to clean, prep, and paint exposed metal on the outdrives. This goes for saildrives and outdrive lower units as well. Sacrificial zincs on outdrives are sized for the particular unit, with the assumption that the entire drive is coated with paint. As more aluminum is exposed, the zinc anode erodes away at an accelerated rate, possibly leaving your unit without protection during what you believe to be a normal interval.
In addition, Yanmar now offers a two piece zinc anode that can be installed without the removal of the propeller. Now, you need to install a SS plate ahead of the prop, which will require the removal of the prop initially, but after that, your diver can change the zinc more easily.