Raymarine Wind st60+

[g5665]

When we bought the boat it came with a St60+ Wind display and windave installed and a old display and a new vane and cable for spares.
The spare vane was already installed because the old one had connection problems.
All was ok until recently when the display, everytime we started the engine with the instruments ON, went blank or with just 3 dots. This started to happen more often and now even with just the instruments on and no interference from the engine starting.
Thought it may be a connection problem but power was ok and data is also ok.
Didnt check the plug on top of the mast yet but it doesnt make much sense being that the source.
Does anyone have any idea of what may be wrong?
We are about to leave USVI to Panama and i would like to have the problem solved.
Buying a new one is out ofbudget...