Hi Jeremy,
I cleaned the pump like you suggested. It had some minor algae/detritus build up, but nothing serious (calcareous). No blockages were found in the system. Since I last posted, it has been running erratic (similar to described originally), and tonight it began making a loud squealing noise followed by complete loss of pressure. I cleaned the pump again tonight (again, no serious build up), and restarted it. It has continued to do the same squealing / loss of pressure sequence periodically (every 30 minutes or so).
Is it possible to initiate an exchange? Please, let's do so quickly as this is the only pump between my display and refugium.
The spark has not been a problem, as I have taken your advice and been unplugging at the wall.
Thanks for your assistance.