Ditto. Are you sure it is the compressor that is being hit?

The fan blades may be hitting the radiator (causing a metallic sound). I had this happen on a 114 250C when the radiator rubbers that hold the radiator in the channels were old and the radiator was able to move back a bit (especially of the rubber rings are still installed on the top). Yanking the radiator forward solved it, until I got new rubber channel inserts.

Check for fresh metal scrape marks (and make sure the engine is off!!)

Good luck,

Bert

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'70 111 280SE/c 3.5 (4 spd manual) - sold
'63 MGB
'73 MGBGT V8