Bit of an electrical burning smell which may get worse on the drying cycle? also, how do you set the self diagnostics running?

if smells like something then something is burning stop using answer about can it be fixed is unknown till diagnosed

If you EVER smell that again, unplug, unload(dry or not, lives may be at risk), preform a thorough check and identify the smell. Then buy a replacement part and check ALL the wiring. Really I cannot stress just how dangerous this is. In my opinion a new dryer would be fine.

2cm seems short for brushes, probably your problem.

Sounds like you have a bad drive motor.All the symptoms point to this, intermittent no start ,noisey when it does run, and most of all burning smell,what you are smelling is the covering they use to protect the windings of the motor, this could be a potential fire hazard I would get this repaired soon or if the unit is old enough to justify replace it

just a quick suggestion
check your exhaust outside for proper airflow

Would suggest that you run the machine empty for a few cycles and the urine will burn off the elements

This may be the smell of Varnish used in motor winding. When we turn on the machine it gets heated a little bit resulting in a burning electrical smell.

Most likely the vent to the ouside is clogged. That would cause the initial not drying properly problem.

If the exhaust is clogged, the moisture cannot exit properly, and it ofcourse, cant dry properly.
This also caused heat build up because the vent being clogged wont allow proper airflow over the element/s and it then starts poping limit switches or worse, burning elements.

The smell was probably an overheated element resulting in the popped switch.

Some units are auto reset. Just disconnect power and reconnect.
Some are manual reset, you have to locate it and push the button. And still others are one time trip, and must be replaced. These can sometimes look somewhat like a fuse.

Trace out the wires (with power disconnected) from the elements untill you find all the limit switches. Disconnect both wires to each side of the switch and see if there is continuity accross it. If yes (the switch is closed) it is good. If not, replace that switch. Be sure to check them all if there are multiples in your unit.

Try Running Goo Gone Through It Although It Smells Like Oranges It Removes Stains As Strong As Sap. Also Try Running The Dry Cycle While Its Empty Two Or Three Times.

Have you checked your outside vent while it was running to see if the dryer was venting 100%. If your clothes are hot and humid I would say clean your vent pipe has a blockage and needs to be cleaned out. Also as far as the burning smell you could take the front off (unplug first) the dryer of by removing 4 screws one above and one below the latch and two at the bottom and there are two clips one at the top left and right push in with a puddy knife and lift the top up a couple inches and lift the front up off the bottom holders. Then you will have access to vacuuming the lint that is floating around the burner.