Before sending it in for a rebuild, I suggest taking the rubber gromet out from
the center of the glass face of the instrument. Then, with a jewlers
screwdriver, adjust the brass screw so that the needle is "zeroed". This might
be all you need to do. If you have another vario, or with a stop watch and
your altimeter, you can get a good idea if the instrument is measuring a
correct climb or descent rate. The Sage is an EXCELLENT instrument. I
wouldn't trade it for 10 Winter varios. The Winter is much too slow compared
to the Sage. Once you get accustomed to a Sage, you will never want any other
mechanical vario.
Rob