I can't seem to get rid of air bubbles in my large stinger baits. I heat plastic to 350-360 I draw plastic into injector not sucking air in it. Inject mix into mold not hearing any air doing it slow enough that it wants to set up on nozzle end. If I ram it in fast seems I get more bubbles. I know there's a learning curve but getting frustrated with not being able to get it right. It's a new injector and o ring so don't think that's it. Or is it just the deal with each try you we I'll have bad ones?.thanks for any advice