Here is a trick I've been told, but haven't tried yet.

Take a 1/8" steel rod for acetylene welding, and put it between the ground clamp and the work. Be sure it is somewhere 'safe' because it will get HOT.

the purpose of this is: the welder will drop voltage across the long acetylene rod, and thus lower the power at the stinger.

Give it a try, and let us know how it works.