Modern Chair Restoration does not stock or sell any replacement parts. Below are the ones most people seem to be hunting for.
EXPERSPRINGS – the vinyl-covered round springs that are in a loop and are found on seats and backs of some Danish Modern style chairs.
Get them at the Danish HomeStore in the UK. This is the only source I know of at this time.
PLYCRAFT lounge chair parts – swivel bases and more.
PLYCRAFT lounge chair glides, feet, and shock mounts