Originally Posted by Tomahawk
With that system it has to be water getting past the check valve, as Old Biscuit said. You didn't say if this was a one time issue or recurring. It could be that the check valve had debris on it that is now cleared and that is why it does short cycle. At the end of the video the guy mentions winterizing valves as potential culprits as well. I never winterized so I don't know how that might work.
Spoke to Pentair (fast response, spoke english
) contracted tech company and followed their advice and replaced the valve cover unit. They said often it is not just the check valve. They don't sell parts either.
So I just replace the complete upper housing. Most places had it for $44 or more. Amazon, suprisingly even for them, had it for $29.