pitot blockage

If the Astir is at all like the Grob 103 twin II the
pitot tube is probably a straight copper tube. Use
some heavy duty safety wire to poke through the insect
debris that is probably blocking the aft part. Disconnect
the pitot tubing from the front and back seat instruments
and add some water to the pitot tube to help dissolve
the debris. After you get some air flow through the
pitot you can blow the water out the pitot from the
instrument end of the system.

Good luck,

MC