Cluster light fuse keeps blowing

I have a 1973 Valiant, recently my gauge cluster light fuse keeps blowing. Not sure why this started, the only thing electrical I have changed recently was the ignition switch and turn signal switch.

The Lights will blow a few min of driving some times or this last time went five days of 15+ min of night driving and finally blew out tonight. Any ideas what may cause this?

I have already changed the headlamp switch and cluster voltage regulator no change.
I also have 3 aftermarket gauges that get their lighting off the illumination wire off the headlight switch and they are bit affected when the fuse blows.

Thanks