McFinn makes a few models of pump. Is it a US-FIP? No suction of liquid could indicate an air leak somewhere, which would typically be fixed by changing o-rings & seals until the culprit is found. If it is a flexible impeller pump I would try introducing some head pressure by partially closing a valve somewhere downstream. Try this in both directions if possible. This assumes you can get liquid to the pump inlet somehow. If it can pump at all and you introduce pressure downstream, any leaks may become visible.
If possible, use different hoses, gaskets, valves, etc. so that the source of the issue can be narrowed down to just the pump head.
We’re not in NY, but let me know if we can help getting you a new pump. We sell a lot of pumps to distilleries. Good luck.