Fuel injector question

[Windward mark]

My old yanmar ysm8 overheated ( no alarm )
It had been hard to start when cold so while replacing the impeller (root cause ) and muffler which melted, I decided to pull the head off and check the valves.
They were a bit rough so I lapped them hoping it would improve cold starting.

Late Sunday everything back together and engine starts easily (yay ) ran for a few minutes then shut down.
I didn't get back out due to violent storms for another two weeks ang now she won't start.

I have bled the fuel again and am getting fuel to the injector.
When I had the injector out to clean it was very hard to get the needle out, had to use a little heat !
Even after cleaning it would not slide easily, I have removed it again while I can get it out it's not easy.

I'm planning on taking to an injector specialist (any recommendations Sydney north)
So my long winded question is:
Could the sticky needle be the cause of no starting ?

Cheers, Tom