Hi Lyman,
I would tend to agree with you on the -900. For this -1000 problem, it is unusual and as somewhat indicated, it was due to a manufacturing process problem, something in the gearbox that was supposed to be corrosion resistant wasn't because a processing step wasn't done properly. Usually the major gearbox problem is oil leakage, not internal component corrosion. Other parts of the engine can be susceptible to corrosion attack, particularly engines that operate out of airports next to the salt water seas and there are many of them. We used to run test engines virtually "on the beach" with the inlet facing the sea to be sure the anti-corrosion coatings on some components actually did what they were supposed to do over the time span required before component removal and servicing.
bvcu ,
Actually, Hamilton Sundstrand is a very good supplier of gearboxes. I am pretty sure the gearbox for the GP7200 engine for the Airbus A-380 has a gearbox designed by them.