Modern Vespa

I ride my GTS into the garage.... However it's really stiff pushing it backwards, like something's binding.

Any hints?

It should roll quite easily. I expect it has not always been like that?
Since when do you experience the issue?

Put it on the center stand and check whether it is coming from the front or the rear wheel. I would expect the rear.
Check if the brake pads come free from the disc.
Check if you hear any unusual noise when you turn the wheel.

Wheels move freely, with no noises. Forward is ok, just backwards. Strange...just in the past 6 months

Probably the bearing see thread below

T5 rear bearing chewed up

Yet it rides fine. Did 400 miles 2 weeks back

Maybe that is why it is possibly failing now

Like it before that.

Well have you checked rear brake cable also, just thinking out loud

No cable on GTS it's hydraulic

My bad I thought he was asking about Vespa VBB T5 should have read GTS, would be good if most who ask questions would actually say what scoot year etc and CC they are asking about, makes life easier to respond.