DAMN Riders - No rules, Just ride!

I have a lawn mower with a cracked aluminum sump. One of the bolts was overtightened and the bolt boss cracked. Its just a hairline crack, no missing chunks or trauma, but obviously oily.

I've tig welded cracked motorcycle crankcases but i never get a crisp stack of dimes. It's always an amorphous goop of aluminum.

Is there any decent soldering rod available aka Muggy weld etc? I have tried muggy weld but can never get the flux to melt the rod and flow before stuff gets overheated and gravity destroys whatever i'm trying to muggy weld.

My tig welder is a chinese pos inverter type and i have no formal training. I'm not against getting a better welder or practicing more etc but maybe there is a magic bullet?

Practice is #1. Though better welders do help. Modern inverter based welders that can do high freq (like 200Hz) and waveshaping (like 20% cleaning, 80% penetration) are a ton easier to use - its almost like cheating. I'm a self taught but consider myself pretty decent. Stack of dimes is purely from pedal based rhythm. Is yours inverter based (can you change the waveshape % and freq to be something other than 60Hz?) And do you have a foot pedal (vs wheel or lift start)?

What alloy are you using? I find 4043 is much easier to use than 5356. Those are the two common ones. Though I do have some crazy expensive high-silicon 4047 which flows like water (had to repair a BMW M3 engine block which is Alusil and doesn't use cylinder liners. So there is a metric crapton of silicon in the alloy. I made him buy me a couple pounds of it as part of the deal.)

I've tried some of those 'magic' aluminum weld sticks but have never gotten them to work. Though that was back with a torch. Using them w/ TIG brazing they might be ok? But you need a welder with good low current control so you don't overheat everything. I have found no magic bullet.

The first thing I'd try is JB weld. If it works, great. If it doesn't, it isn't that difficult to clean off and then do the welding or brazing you're trying to do anyways.