Having issues with my trailshot. only used it once and it worked fine. After a night away when I returned I went to flush clean water through it, it appears that it will not suck water through. I have performed an integrity test and that was ok, but still it will not suck water through. If I remove the filter cover and orange valve I can get some water through but when I reattach it will not work. When I remove the hose and manually suck it will flow, again when I reattach the hose it won’t. Anyone any ideas? Have emailed msr but the auto response email says it could be a while before they reply.