System - Dionex Ultimate 3000 UHPLC
Software - Chromeleon, Hystar

1. Purged A and B for 30 min.
2. Run left block only, 0.6 uL/min flow gave 7.5 bar with 89.1% A and got output from the mixing valve.
4. Purged B 10-mLs collected in 20 minutes collected purge in graduated cylinder.
5. Purged B second time, 30 minutes.
6. Tried to re-run B but still 0.9 bar and no flow from the outlet.
7. Increased flow to 0.9 uL/min still no flow, 1.3 bar.
8. Increased flow to 1.5 uL/min still no flow, 1.9 bar, no outlet.
9. Increased flow to 1.5 uL/min still no flow, 99% B, 0.5 bar, no outlet.
10. Switched B to A, purged 30 minutes.
11. Now B is A flow to 1.5 uL/min still no flow, 99% B, 0.7 bar, no outlet.
12. Got output from the pump line going into the mixer.
13. No outflow from Loading Pump.

Does anyone have an explanation or suggestions for things to try?

Many thanks