Most drive cables can be pulled out of the housing from the speedo end, no need to disconnect at the transmission. Give the cable a good wipedown with a solvent-soaked rag, and coat it with fresh lube as you reinsert it into the housing. If that doesn't improve things, and there's no tight bends in the housing, there's probably some roughness inside that the drive cable is hanging up on.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!