Have had starter squeal twice, around 30,000 and 123,000 miles. I removed starter, took it apart, cleaned and repacked the planetary gears and all moving parts.The old grease was contaminated and sticky. I also lightly filed the teeth where they engage the flywheel. Be sure to lube the lever and spring that work off the solenoid. I pack the planetary gears by filling the hole with grease and holding my finger over it while pushing the gear back on the metal pin. I am still using the original factory starter.