Sounds like the idler wheel and or idler bearing are worn. It will cause variable tension.
However, if your blade “bucked” as you say, it sounds like it was clogged up, maybe using too fine a tpi for the thickness.
You should have no less than 3 teeth engaged in the work and no more than 24. If you’re pushing so hard that one slip takes out a lock panel, your blade is likely too fine and or clogged/damaged.
Broken and damaged teeth will also cause issues. Make sure the blade doesn’t hit anything hard when opening, don’t throw the blade and run.
Also, buy quality blades, don’t cheap out on this. I know because I sell them for a living.
Hope that helps.
-Ryan