Stihl MS180 chainsaw, new, but not starting?

Stihl 180 chainsaw which I bought two years back, never used, and am now trying to start. No joy.

Good spark from the plug (take it out, lay it on the cylinder head, crank the engine, series of sparks visible across the gap.

Fuel getting through, can smell it in the exhaust and if you take the spark plug out it's wet. There's now a sloshy buildup of fuel in the exhaust baffle thingy - I'm assuming this is normal for a 2-stroke that's been pulled through 10,000 %£$*&!! times without firing ? All my engine knowledge is on 4-stroke so I'm kind of winging it here.

I feel this is a carb problem. First pull on the starter after leaving overnight and it catches for a dozen revs and then dies, won't give the slightest sound of catching after that. Too much fuel ? Plenty of compression, or feels like it. Have replaced the diaphragms in the carb with a service kit in case they perished, needle is free-moving.

Is there anything else that gums up / perishes when one of these sits for a long time ? Anything else I can check ? I could take it in to be fixed but this has become personal...

Richard