My NP 241 will fall out of 4-Hi. I’ll be driving along in 4wd in snow and all of a sudden I’ll lose traction and realize it’s back in 2 hi. I think there are some plastic bushings on the shift forks that may be the culprit? Does this mean full rebuild? I have the t-case out now so it’s probably a good time. Everything else is OK except input and output seals. I was just going to do those and call it good, but now I’m thinking I should crack the case and at a minimum replace anything plastic or rubber. If there is agreement I should crack it open, any good advice on rebuild kits? I’m thinking the chain should not need replacement?