XJ6 X300 1997 - Rear interior lights

[Raffles]

Another probably well known fact that I'm yet to learn... 

Rear interior lights don't work. Changed fuse, no difference. Front interior bulbs all work. 

Pulled out the rear interior light modules to check the bulbs indoors. 

Yesterday I got 2 modules from a scrapped Jag in the scrapyard. 

All bulbs are good. But noticed a difference between them:

Original Right module doesn't have a spring - the rocker switch - but when assembled, you rock switch it on and the lense stays depressed. Press it again and the lense releases. 

The spare Right module has a spring and rocker switch depresses the lense and pops back out. 

Which is correct?? Original with no spring or spare with a spring... 

Original and spare Left modules both have springs and work the same. 

Thanks, 

Donna