Siphon-Feed AB Paint Spill Problem

Have you tried backflushing the brush? Hold your finger (or a rag/or wad of paper towel) over the air tip and depress the trigger. You should see bubbles in the jar as it blows the paint back down the paint path.

I backflush with alcohol to clean the AB. Am I supposed to backflush before taking out the bottle?

I don't use my Paasche H much anymore but when I did this is the procedure I used:

Removed the bottle containing paint

Held the brush 'nozzle down' and sprayed what was left in the nozzle/needle into a rag or container

Wiped the inside of the nozzle with a Q-tip, Cotton Bud or such

Attached a bottle containing thinner and  sprayed until clear into rag/container

Probably lots of methods but this worked for me.

I don't use a Paasche, I use a badger siphon feed.  I do get drips when I  take off bottle.  Realizing that will happen, I always remove bottle while I hold the airbrush over my waste can.  If I have enough trash in the can I then touch the feed tube to something to soak up that residual paint.  In the rare circumstance that the waste can is empty, I daub end with a piece of paper towel. I always keep a piece of towel on my bench whenever I am airbrushing.