I would replace the stupid thing with something else...
It's hard to tell if the 2.5 is low on compression due to the EZ-start, unless you have taken that off. But, if you can easily rotate the flywheel in complete revolutions with the glow plug in when the engine is cold, it's probably time to rebuild.
I meant rotate the flywheel with your fingers... if you can do complete revolutions with the glow plug in easily, it's probably about dead.
Another couple other tell tail signs is that it won't idle low worth a crap without stalling and it will flame out all the time when engine temps get up to running temp.
You can send the piston and sleeve for a "pinch" for 9 - 12 bucks, or buy a pinch tool for about $40.
If you're interested in the pinch, someone will give you the guy on Ebay who does it. You can do this 2 or 3 times with a sleeve. It's still the same amount of work as a rebuild kit, but a lot cheaper.