Great to see that our beloved bike has such a helpful community.
I have been driving my TTR 250 for 2 years now. After a recent fall over my gear lever would not return to the central position. So I have took it apart and realized that my return spring post is broken out of the crankcase.
It did happen to the OE i have years ago . I effected a repair back then and a few years ago i bought second hand cases from Brian here and rebuilt the engine . It does happen them and as previously mentioned TIG welding should sort it if you lay the bike on it side.