I have one of those antennas. If it's high SWR on all bands, I'm guessing that it's a coax problem.
Swap the coax and let us know what the result is. The outboard parts of the radiating element aren't even seen , say if you're operating on 10m, so if it's that high on ALL bands, it's probably the most simple reason...
Bad coax or coaxial connectors.
Disconnect the coax at the feedpoint and connect it to a dummy load and see what you read.