Star Commander I, help please!

[Farlander]

I'm stuck in Star Commander I. I got to the city of Telbin. First I sold the old hyperwarp inducer for 50 zeltar. I tried to buy a new inducer, but it cosed too many zeltar. Then I buyed a disk with information on sector LH (a man from star command told that sector) for 30 Zeltar, and a gas grenade for 4 zeltar. Also I found a screwdriver in janitor closet in the bar. I'm stuck, and don't know what to do.