the rubber seal on the ps rack is broken
are you talking about a seal or the DUST BOOT - big difference
refill fluid ( use auto trans dex2/3) & see where it's leaking from
-if you drive around dry too long , I think you can fuck up the pump.
-the high pressure (rubber) hose is a more common failure in older cars
if the actual rack is stuffed - if your lucky u can find a good one at Upullit - for $95 ( I did a year or so ago) - much easier(cheaper) than rebuild.
not really sure how to use a tap and die
just need a tap - take a screw(ROCKER cover) and get a tap thats the same size/thread pitch and rechase the hole - that may be enough - if not then get the next tap up (ie wider & new bigger bolt/screw) - if that sounds too hard - get the mechanic who buggered it to fix it for free