TC reported MCH jammed while switching in between RMF to ATPM. TC repeated switching several times a nd was able to proceed in ATPM to headwall. ~~~~~ 3550 TC reported MCH jammed while switching in between RMF to ATPM. TC repeated switching several times and was able to proceed in ATPM to headwall. CE: 3550 Check MCH slightly stiff. Serviceable  3550 found mode selector was stiff when switching to RM to ATPM causing the MCH become stiff. 3550 Check mode selector position mechanism was dry(No grease). Apply grease and retorque the bolt. Functional check mode selector and MCH ok. Done by Zulq 45180