depending on which pump you may take out 4 retaing bolts hex head and if its older type clean off face clean reciever body and refit ( dont forget to turn off isolation valves ) before undoing and isolate elec if it continues you eill probably need a new pump however grunfoss are very good and can go on for a long time although annoying however continued hitting with an hammer could cause leakage to joints you have been advised good luck!
bluebird4211
April 2008
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