its bad to let any vacuum sit for long periods of time. without use the bearing grease degreades, sleeve bearing oil dries out. usage keeps lubricants hot and fluid so they do their job.
if you add poor storage conditions into the mix, humid basement, or extreme heat. can make parts like carbons stick. not to mention nasty rus or siezing or functional components.
your tradition looks like its inside, so the elements at least wont have at it. use it once every 3 months at least. to keep bearings in good shape. even if for just a few minutes.
if its not a machine you love, consider re homing to a collector who appreciates more?