sogamla

I have a 1990 model S4 automatic. Recently, I had to change the metal line between the PDS solenoid and the slave cylinder as it had split. Not having a Bosch Hammer, I used the Louis Ott and John Veninger method to refill and flush the PSD fluid. The reservoir is full, the pump works fine (as far as I can tell), and the locking solenoid seems to be under pressure when I open the bleeder valve, but I must admit that the break fluid only drips out of the slave cylinder when, as the last step, I tried to flush it. I am not sure if this is normal or not and would be grateful for comments.

The car drives fine, but the problem now is that the green PSD light goes on frequently with normal city driving. What I have noticed is that if I stop and take my foot of the break pedal, more often than not, the PSD light will light up and then go off when I press the break pedal again or start driving. On one or two occasions, I feel having stopped that the brake pedal is vibrating under my foot (? something to do with the ABS which I gather is linked to the PDS in some way). I haven't had the Slip Differential Off warning or any error message about the ABS, however.

Any thoughts on what I should do next to sort things out?