I have read many complaints about antennas only going up 15 inches, or 30 cm. Mine was doing this (seems to be a common problem), and this is how I fixed it for free, at least temporarily.
This is the Hirschmann 6000 EL off my newly acquired 1990 TE. The mast would only raise about 30cm, so the PO allowed the mast to get corroded in that position. When I replaced the mast, the problem was still there. After reading a couple of threads, one in particular was great about what wire did what, and coupled with my cd manual, was able to determine that the circuit board has a problem.
Without going into all the gory details, all I had to do was open the antenna, pull off the white wire from the circuit board and tape it off. I then pulled off the blue wire and plugged it into the spot where the white wire was.
What this does is it makes the dash antenna switch useless, but the antenna raises fully and lowers with the radio as it should. What it also does, I did NOT mess with any of the vehicles wiring. So when I get another board or antenna, or the next owner does, just slap it in, and you are good to go.
Hope this helps