electrical problem, gilera stalker 03 plate.

I am attempting to keep maintained my grand daughters Gilera. there a couple of electrical issues which may have been covered elsewhere (direct me if you know)

Problem 1, when it's been raining or the air has a very high humidity (I live right next to the sea) it won't start, plenty of battery, spins over well but no life however occasionally in these circumstances it will kick start. When conditions return to dry or even proper rain it works perfectly. I have made sure all the protective covers are in place and liberally sprayed with water repellent.

Problem 2, which may not be unrelated, the other day in the red hot weather after a few hundred yards from first start of the day it slowly petered to a halt started by running erratically then just came to a stop. again plenty of battery, turned over very easily but no life however after about 30 minutes it started on the electric starter a bit reluctantly and got me home though it wasn't it's usually happy self. Yesterday I went up a hill and it had only about 70% of it's usual zap.

About three months ago I fed the power for the headlight through a switch (the proper Gilera handlebar one available for foreign market versions) so now I can switch the headlamp on and off leaving only the small sidelight and tail light on all the time, I did this because due to the constant stop/starts she was making because of her job the bike was not making enough between starts to keep the battery charged up. Now there is no problem however I am thinking I may have been slowly frying a part of its electrics by feeding in too much current.

The sea air had got to the circuit board in the instrument binnacle, I have managed to recover it however the 8 small bulbs are all knackered, I need new ones, the holders contain 2 tiny springs that have corroded away, I am trying to find the complete bulbs and holders. Can anyone direct me where? And are they all the same wattage? Every dealer I have spoken to says they don't stock them but I'm sure that with a pattern number I could buy them from a bulb manufacturer like Ring, anyone know what the type number is?

All constructive comments gratefully received.