Mark V Model 500, Serial #321013 makes Bad metal-scraping noise.

[JPG]

I think much of the 'rattling' is caused by play between the key(s) and key groove(s) in the pulley sheaves. Four places for it to occur. When wear increases that play, the vanes on the sheaves may bang into each other.

[chapmanruss]

David provided the link to Everett's Google Drive where you can find the first three Mark 5 Owner's Guides restored as PDF's. The Owner's Guide that originally came with your Mark 5, which was made in the Spring of 1955 based on its serial number is the third and last one Everett restored so far. Several changes occurred from the introduction of the Mark 5 and when yours was made. On the Headstock drawing you will see part number A3274 Retainer - Bearing which helps hold the Idler Shaft Bearing in place. Check to see if it is present. Without it changing speeds tends to push and pull the Idler Shaft in and out of the mounting point of the Headstock Casting. This could cause a metal scraping sound not yet mentioned. Over tightening the Cap Screw & nut that holds the Idler Shaft Bearing in place can break the Headstock Casting which is why they came up with the Bearing Retainers.