Yes, on our club's Twin Astir we can access the back of the pitot tube
by removing the rudder and then using a pair of forceps, or a small
hand, to disconnect it. Once we had the rubber tube disconnected, then
we could clean out the blockage with a piece of heavy gauge safety
wire, and blow it out from the instrument side (make sure you
disconnect all the instruments before you pressurize the line or you
could cause damage to them). We also have a small filter installed
behind the panel to trap any small particles or water that gets in the
lines. I hope it is as easy for you as it was for us. You may be able
to do it without removing the rudder if you find a good stiff single
strand wire that is flexible enough to make the bend in the tail and
then blow it out from the front.

Adam