Dash lighting inc cigarette lighter bulb and heater bulb

A frustrating day trying to get Dj Ev 's dash lights working.

We managed to get the 3 binnical bulbs working along with the light switch and bulb. Rheostat working properly. 

We were left with the inoperative cigarette bulb and heater control bulb. We had power to the connections.

My question being - does the circuit have to be 100% working for the bulbs to illuminate? 

I've had a search through the forum but can someone remind me which bulbs can be changed and which require the bulb and holder please.

Ta

The Cigarette Lighter lamp is on the side of the Ciggie lighter.

see: I like this one Bestest
https://www.vwvortex.com/threads/led-dash-lights-tech-procedure.5305799/

The Fascia is similar to the corrado.
Replace VW Corrado Heater / AC Control Light with LED Bulb - YouTube

Read all the way through
https://www.vwvortex.com/threads/88-cabby-heater-control-with-non-removable-bulb-mod.7081949/?id=7081949&highlight=heater+control+led+led

Found this link,
https://moman.pl/en/home/877-1918-volkswagen-corrado-heater-control-panel.html#/191-lighting_color-white_sky_blue/302-version-with_a_c