• If the battery is charged but the electric start button does nothing 
• beep the horn! Yes this does work but not sure why. It must be something to do with them both being fed off the battery.
• if you are new to Vespas, turn on the key and pull in the clutch lever

• Head light does not work but both low and high beam panel lights show as on (can be intermittent and correlated to wet weather and/or turning)
• the black wire going from the light switch through the headset stem has been broken or shorting (due to headset side to side movement wearing through wire insulation)

• Indicators intermittently stop working but the panel light shows them as operational
• change the flasher unit
• One indicator stops working intermittently (panel indicator light stops also)
• may be caused by bad connection between side panel and frame. Clean brass contact point "spike" from side panel and female frame connector with cotton bud. 
• may be caused by the plastic chrome shorting it out (or dodgy flasher unit being sensitive to resistive shorting) - replace indicator and/or flasher unit

Rear Tail Light

• White spot appearing in plastic
• Using the wrong size bulb and the bulb melting the plastic