Press the blub into the socket at the same time turning it over towards the machine as far as it will go: them withdraw the bulb. To insert a new bulb press the bulb into the socket and turn it over from the machine until the bulb enters the notch in the socket. The bulb is difficult to get a hold of, I used a piece of rubber tubing to be able to get ahold of the bulb ,push and turn. I thought it was my bulb but turn out to be a connection. Check out David McCallum's website
www.Featherweight221.com. It has a lot of info. Hope this will help some.