Possibility 1. Resin in riser tube (less likely).
2. Sounds daft but did you put something over the riser tube to stop resin getting in - then forget to remove it?

3. When replacing a fitting, you used a faulty one or damaged the original.
4.Kink in hose or pole hose?
Remedies.
1. Remove resin from tube and try again.
3. Replace the fittings one at a time. Do it systematically. Keep the originals in case this is not the problem and they are OK.
There are other things to check but they wouldn't relate to a resin change.