Well I didnt need a magnifying glass to find the problem. After changing the impulse line with no results, I carefully pulled out the fuel line:
Right where the line comes out of the tank and does a 90 degree turn to come thru the carb floorplate I found a large hole. I repaired the problem using a new fuel line and filter from Baileys. The repair went fairly easily using advice from here at AS.
Remove upper and lower top end covers. Remove carb from floorplate, disconnecting choke lever and throttle cable. Remove 4 screws securing floor plate to lift it up enough to see the tiny hole in the top of the tank, below the floorplate fuel line hole but at a 90 degree to it. I used a piece of safety wire about a foot long and snaked it down thru the floorplate hole and fuel tank hole, thru the fuel tank and out the gas cap hole. I heated the safety wire and burned/poked a hole thru the end of the new fuel line, (curled it closed) which came already cut at a nice 60 degree angle or so. I then fished the new line up thru the fuel tank hole, and floorplate hole using a pair of extended and 45 degree angle needle nose pliers. (Regular needle nose should work fine.) My daughter held a flashlight during this part so I could see between the gap in the pryed up floor plate and the tank/handle assembly. Before the curled fuel line disappeared into the tank I pushed on the new fuel filter. I then pulled another another inch or so up on the fuel line to give enough length to attach to carb. I then reinstalled the carb, floorplate screws, cable and choke lever, filter and top covers. I poured a touch of gas in the carb first before buttoning it up. It fired on the second pull, and started on the fourth pull- good as new. Thanks to all those who gave advice and previously posted the wire trick to fish the fuel line up thru the tank. Without that it would have been damn near impossible. I ran the saw 30 minutes later, all good!