Comp tester is an automotive style, first time I tested it against a known running 465 xp, three pulls got me 115 on the 465 and 120 on the echo, rechecked with 6.pulls and got 120 on the 465 and 135 on the 3510, i habe also aeem on here that 4 stroke tester can read low on 2 stroke engines. I never did get it to fire with the coil off the 310, but upon reinstalling on parent saw it fired right up. I go hookes a timing light up to the 3510 and ran it off a car battery and a drill and got trigger. Unfortunately I don't know what correct timing would be and don't have a degree wheel to call out measurement. All I can think of is that the coil off the 310 is set for a different trigger delay than the 3510 can work with. Goint to bite the bullet and get a new oem coil, and if that don't work I ll warranty it. I got it through HD so there is no service. It's a drive to the nearest auth. service place. I did happen to go pick up a new echo 590 and I have to say, what a difference! bought a gallon of premix and ran two tanks through it, got to open it up in wood today and I m in love! Cork oak, valley oak and eucalyptus didn't even bog it. I was knocking 16" rounds off of 32" logs without breaking a sweat. And the gas stank is massive! I cut for 45 minutes before needing to refill. I love the saw....a little pricey for me, but no where near what a 60cc Stihl or husq would have run me. Only.complaint is no primer bulb, but I havent had any problems starting it(except when I forgot the off switch was fixed instead of momentary).all. I cut is seasoned firewood, hard and soft, and so far(1 day) it's chewing throigj the wood like it's butter. Anyway, I ll update when I get the 3510 running again.