TC reported Cab door 'B' side stuck halfway when opening. ~~~~~ 3623 TC reported Cab door 'B' side stuck half way when opening.  3623 B/S cab door no FC. Check and found actuator open speed lock nut loose with air leaking. Tighten lock nut, no air leak. Adjusted cab door speed - ok. Cab door able to open/close fully and function with no abnormalities. DIR able to extinguish.  Sarma/Alan/Lee PT/Anand 45281