We do not want to ever overheat a mold as it could warp...I like to set the mold I am going to use on top of my lead pot and rotate about every couple minutes while the lead is melting....I like the mold just warm enough to be a little uncomfortable to load hooks.I use disposable nitrile gloves while working with lead for safety and also for the heat shielding they provide.
Anyway good luck.Another idea is to try heating your lead just a little hotter as a guy should not have to modify a mold to increase gate size.I have modified molds for larger hook size though...

Sent from my SAMSUNG-SM-G891A using Crappie.com Fishing mobile app