try analysis, file the pin holes and see if they open up into some corrosion inside the line.
You are lucky it wasn't the reservoir that you had to replace. Last time I messed with one of these the nipple for the return at the bottom of the reservoir cracked where it comes out of the body. No way was I gonna try to glue that stuff together. Luckily I know someone that has a bunch of parts and he had one (cheap). Buying a new one would not make me happy!

__________________
'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!