Neither the type of lubrication nor the ignition mapping have anything to do with the sprag clutch failing. It fails because of the zillions of small "kickbacks" when it is in there, mostly because of the drag it imposes on the crankshaft.
It should take about 30 minutes to take it out, and then about 20 to put everything back together. If you use an air or electric impact wrench, you don't have to immobilize the drive train. (I got a cheap-o electric 1/2 drive one for $19.95.)
You will need the gaskets. The first time you take these off you will probably have to replace them - from then on, if you just scrape the mating surfaces with a razor blade, you can keep using them over and over.
If you just take out the starter, the offending component is still in there, and in it's present condition (if indeed it is the problem) it will drag on the crankshaft, causing running problems like hard starting and stalling out. I speak from experience.
You have told us that there were already loose pieces in the primary drive. If you wait to see whether any more come loose you may regret it.