How to Access BSA/Triumph Unit Single Gearbox

How to disassemble the primary and timing covers in order to access the gearbox of BSA models B44, B25 or Triumph TR25W to diagnose a gearbox/clutch issue with selecting 2nd gear on my 1968 BSA B441 desert sled.
#BSA441 #BSA #BSAVictor #BSAShootingStar #Triumph #TriumphTR25 #desertsled