I am a little confused as to which light you are referring to: you've had the side marker light removed… the indicator lights blink happily on demand. So which one just lights op permanently if your headlights are on?
Anyway, if you've had a repaint done, then chances are:
- you've developed a bad or intermittent ground connection
- your painter removed connectors, and wired them up incorrectly.
I've had something similar before… two wires were swapped on one of my headlight connectors. When lights were off, blinker lights appeared to work. When lights were on, they did not. Essentially there was a short between the +ve of the headlight, and the -ve of the blinker. When headlights were on, applying +ve voltage to blinker created no current flow, hence no light.
I would therefore suggest that you have a bad ground connection. To be able to troubleshoot this, there is a useful document on this page of the Wiki:
http://www.sl113.org/wiki/Electrical/Connectors (in the green text, the link: Connectors and Leads of the Main Wiring Circuit). Find the correct connector and ensure that all wires are connected where they should be. Make sure you orient the connector correctly when inspecting…
Peter