Stihl MS881 won't start normally

[PretzelBites]

My pops got this old Stihl MS881, it's like two decades old with a 30 inch bar, is a total pain.

It fires up fine without the bar and chain, but the second I put the bar on, it just won't start. But if I hold up the bar's weight, it starts and runs perfectly.

It's gotta be something with the weight of that 30inch bar messing things up.

I had never repaired a chainsaw before, nor had my pops. What should I do with it?

 

[Stihl 99]

Hello
This is a very odd situation you have brought here, it sounds like the internals are gone, take it to a Stihl dealer and have them run a diagnosis.
Also you say decades old, so the MS880 is a very good saw.