Drive belt (lower belt) for Shopsmith Mark V (1953 to present)
The drive belt is very frequently needed. Replace it when the width of your belt across the top is less than 1/2" so it won't be pinched in the sheaves or make the machine run at incorrect speeds. Replace if the rubber is cracked, or if strands are sticking out.
This style of belt is one of my favorites to use. It has a cogged edge (see photo) to help prevent "memory" when the machine is used infrequently. Belts can get a distorted shape which affects performance until that shape gets worked out again and the belt is flexible.
See the 2 free short videos on my website for drivebelt inspection and how to replace it.