Antenna makes horrible grinding noise and does not move in '90 Integra

I have a power antenna on my 1990 Integra GS and when i first bought the car (used a week ago) the antenna would not move at all, it would just make a HORRIBLE grinding noise and it would not move. I tried dropping some WD-40 on it and making sure that it gets inbetween the separate parts of the antenna and that it is all lubed up. This helped the problem, now the antenna will go all the way up from the bottom position (but still makes the horrible noise for a second after it finishes fully extending) on the way down, at about 8" from reaching the bottom, it gets stuck and makes the horrible grinding noise. The next day, it didnt go down as much anymore and it is back to being stuck near the top
any ideas?