1997 prov 150 speedo doesnt work

i bought a sundancer 26od tritoon in aug of o7. firs time out the speedo worked fine,next weekend it doesnt worke at all. it is digital and all other funtions work fine.i took the tube off where it enters the lower unit and blew air back to speedo and it regitered fine. i blew air the other way to clear any blockage but it still wont work. is there a way to clear or replace tube into lower unit without removing the unit? i cant find any info in the motor manual.

[jb123]

most likely clogged, use a small drill bit by hand to clear it.