Modern Vespa

Bought ET4 3 months ago with 2900 miles. Put on another 300 miles on, replaced shocks (Bitubo) and tires, 50% front break life, 75% in rear remaining at service. Have noticed increased break squeak from both front/rear breaks when applied, especially as stopping. Is this dust build up, can it be easily cleaned or recommend from authorized dealer? I don't think the pads or rotors are totally worn?

Your front breaks, you may have some corrosion built up on the piston, take pads out pull on break lever to piston is fully out, clean off any corrosion with wire wool.

rear breaks could be a build up of crap in the wheel surround, clean up and scuff the rear shoes bit of emery paper.