Petrol strimmer engine trouble

I have a fly mo x250 lite petrol strimmer

I have it about 2 years now and it was working fine until it cut out whilst I was using it last week

I couldnt pull the starter (felt like it was locked) when i opened it up all look fine but the cog it was connected would turn with a lot of resistance. I put some oil on the cog and turning fine now.

When i prime the bulb and attempt to start now, the engine wont start..
I can hear it trying when i pull on the starter but never gets going.. I dont know a lotabout engine's but fully willing to open up and have a look... worst case I am due a new strimmer anyway...

The local repair guy, who doesnt like people he doesnt know said its near impossible to sort problems with strimmers and barely looked at it for more than a second.

This drives me to try and look at it myself... can anyone help?