Ah, the self-cleaning needle could very well be blocking the flow and that's why it shuts off in that direction also. I'll check if mine has one.

By the way, the wikipedia entry on the SVEA 123 says the opposite about whether the older or new has the angled spindle.

"These older models are distinguishable by their downwardly-angled spindle, which houses the control valve and to which the adjusting key is attached. The spindle on a Svea 123R with the self-cleaning needle is at a right angle to the stem."