Modern Vespa

Bit of a long one....
Mate bought a banger GT125. It would run great until up to temp then nothing until it cooled down again. I changed plug, HT lead+cap, coil and some other bits to still have the same prob.
Sent it to garage for diagnosis, they changed vacuum petcock and pump. Still the same so was advised to change stator, so a new one fitted.
Now it does not start at all.....will occasionally run for about 2 seconds.
I've had enough...I need help!!
Any ideas?
Thanks

Have the valves been adjusted?

You can start with the basics, pun. Pull the spark plug, is it wet with fuel or dry? Get a known good plug stick it in the boot, hold it against the head and spin the engine. Do you have spark, yes-focus on fuel, no-focus on ignition.

Let them know here which one is missing and someone with experience with your model, Elvis, will guide you in the right direction.

Yes I set the valves as one of the first jobs. Took the carb off to check today and all seems OK. Sparks are good so I thought fuel starvation but that is good too. I is stumped.
Thanks