Bought my first tattoo machine and I'm lost! Help!

Ok, so. As in the title. I bought my first two coil tattoo machines. Watched a lot of tutorials and read a lot about setting the machine correctly. Yet I cannot find any answers for what I have problems with. (Reason why I'm here ).
So. I tried setting everything up and it all seemed fine. I started my first piece on fake skin, and that's when problems started.
I heard that tatto machines should be working without problems somewhere around 7v. My machines started working only around 10-12 v and got hot pretty fast, maybe around 30 minutes of work. The sound is alright for a second, then it changes, as if the armature bar isn't touching the coils anymore when working. So kinda like it's loosing voltage somewhere. First I suspected the pedal. When I press it really hard it seems like it increases the power and it's not constant. The ink stops flowing and it just looks like it has too little power, which seems ridiculous since it's set to 11 v. I'm not sure what else to look for to fix the issue. So I hope maybe someone has some ideas

Firstly different machines work at different volts, for Example I run Micky Sharpz machines up around 10v and some other coils around 6v….they shouldn’t get hot.

Maybe take a video of the problem….there are so many things it could be.

Most tuning relies on the tension you put on the back spring (different to gauge) and the air gap you have between the bottom of the armature bar and the top of the front coil, when idle. This is of course a vast over simplification, but two areas to explore as a starting point.

It's hard to diagnose what's wrong just by a description, it could be any number of things....could be as Whippet has said in the above post, or could be something as simple as having too much tension on your elastic band, or maybe a faulty capacitor if it gets hot very quickly.