My 1975 vintage Dunhill Rollagas burns perfectly in all respects except when I get down to (I guess) about 1/4-1/8 tank of gas; at which point the flame initiates at its normal, preset level and then shrinks down after about 10 seconds. I can adjust the flame back up, but if I do so then when I next open the lighter and spark it, I will get a very tall flame for 10 seconds, which then shrinks down to the new set level.
Is this just typical for a Rollagas running low? Or is it symptomatic of a pending rebuild? Once I fill the tank again, all is normal; and I'm only using Dunhill butane.