Inevitably a day to fix the head / replace the belt. So, knuckle down, clean out the pipes and dismantle the entire head and tubes. The belt looking like it is ready to break - and yet ONLY 6 months old - a replacement fitted. Re-assembled ..of that screw that dropped down the proverbial hole - meant another dismantling to extract the offending article. Job finally done - just in time for the sunset...sundowners and a bbq - cold but delightful!