Started working fine then stopped, full of hardened chocolate now.

@karenpinkston chocolate melts at around 40°-50° celsius (105° - 120° F) Use your oven. Turn the temp to the lowest setting and place your chocolate fountain inside. Leave the oven door open and monitor your chocolate. Once it is starting to melt you can remove it by the spoonful.

If your oven is not big enough, use your hairdryer. It'll take a lot longer but it is easier to manage and you only will need one hand for the hair dryer or hot air gun which leaves the other free to eat the fruit of your labor. Just keep teh heat moving and don't just blast one area. For the final clean you can mix Vinegar and water 1:1 and then use that to clean off the rest.