Thud
I don't know the exact details but having done the job you describe I know that it was an incident with the blow hole on Skerryvore which can be quite surprising in a SW swell. I think whilst on the pad the blow hole blew deluging the 105 rendering it unserviceable. I think it was there for quite some time before Ferranti managed to recover it.
Speechless can fill in the gaps.