Royal 4000 light bulb issue

[kirbykid63]

Hi all just found another royal 4000 upright,I have replaced the light bulb and it doesn't light. I have had this problem with all the royal upright 4000's I've owned over the years. The replacement bulbs have the two contact points and are push and twist type from steelcity vacuum.
Could i be using the wrong bulb for this machine?

 

[human]

I have no direct knowledge about this model but there are two things worth checking:
1. Do the positions of the contacts on the bulb match those on the socket? If not, you may have the wrong bulb.
2. Have you checked for broken wires? It's entirely possible that there could be a design flaw with that model that causes the wires to fail. If you can access the headlight socket while the machine is pugged in and turned on, you may want to test it with a voltmeter to see if the socket is receiving current.