I’ve got a Campbell-Hausfield 5hp air compressor that has seen very little use since purchased about 3 years ago until I put my shop together in July of this year. Lately when blasting, after a half hour or so, the compressor starts shrieking like a very loud balloon with the neck being stretched if you know what I mean. It does it when the compressor is not cycling, so I know it’s not the belt or bearings in the compressor. The noise may go on the whole time, or it may quit after awhile. Any idea what the heck that is?