Kenmore 800 electric dryer burning smell

Wife said she smelled a burning smell from dryer, it's a Kenmore 800 electric dryer. We bought the house a year ago so not sure of its age. I decided to disassemble it witch was a lot simpler then I thought even took the drum out vaccumed out everything, motor, floor pan area, blower motor and houseing, and ducts. When it was apart I checked all the rubber rollers tension belt anything that moved all seemed good. I was surprised how little lint was inside the machine so I went ahead and took down all the exhaust duct seperated it to sections and cleaned it till it looked new. Found a reasonable amount of built up but nothing alarming in the ducts. Reassembled everything turned it on with no heat checked for flow to outside flap and was great. So being that I never actually verified this smell I gave it a test run turned on the heat ran it for 5 seconds opened the door and there it was a burning smell.... Now you can't smell it from outside the machine only if you open the door and stick your head in, I did not check it with heat off it lingerd to long to be sure. Now the heating element works it glows bright red and blew it off with a air compressor (when machine was cool and unplugged)
So I'm pretty much stumped at what it could be does anyone have any helpful insight? sorry for the long post just wanted to cover everything I did.
*also ran on high heat for 30 mins to see if it would clear up no luck

Do you think it's electrical or lint?

Honestly I would be just guessing but it smells like dirt is cooking on the heater elements but there is no visiable smoke, it reminds me of a mix between burning hair and plastic. I tried running it again and opened the bottom kick panel and can't smell anything in there just inside the drum after it been running. I was hoping to see hair or something on the heater element but no luck

Just a guess but, pull the unit away from the wall, unplug it, inspect the blades on the cord/plug, turn off breaker to dryer, remove cover plate from dryer receptacle and inspect the outlet. Your looking for melting, arcing and charring. If you see any of this, replace the outlet and cord as necessary.

Is it running hotter than usual, there is a thermostat that controls the heat.

So just in case anyone else ever has this issue and are like me and chase there tail cleaning every vent checking air flow and testing resistance values checking pullies and belts this is what my issue was, so simple I overlooked it completly, there was one of those stick on bars that help with anti static and also acts like a fabric sheet well there supposed to be lifetime but the glue that held it onto the drum for the past 5 years I guess decided it was time to cause some smells and issues. It's been there so long I didnt even notice it anymore toatally over looked it as a possibility and BAM it was right there in my face the entire time. I was just so focused on preventing a drier fire I over looked the obvious. Thanks for all the help to who replied