Hot End Cleaning tools

I’m starting to get prints that have some layers that are being under extruded so it looks like it’s a hot end tear down and cleaning in my future…

This is the stock ender hot end and I was just wondering if there are any mandrel type tools available to help clean out any filament from the bowden tube path before re-assembly?

Quite some time ago I followed the Luke Hatfield hot end mod with the short peace of tubing and washer and it has working great until I have a jam due to a “knot” in my filament that somehow made it all the way to the hot end.

Long story shout, I striped the hot end, cut out the “knot” (picture to follow) re-assembled and finished the print. ever since then I’ve been having weird issues with my prints, mostly under extrusion at random layers.

I had some problems at first here and there but after reading a few post I decided to buy cleaning filament.
The one i’m Using now is from ESun and im really happy with it, Once in a while I run it through the printer.
First at 210 and run 100mm then I increase it to 10 degree lower then the max temp and run another 100mm through it. I let it cool then warm it up a bit to do a cold pulled.
Good for when you change type of filament and also some colour change.
I did notice after the first few mm of filament does not stick well but I now does a purge of filament before I start a new print after I use the cleaning filament.
It has worked for me very well so maybe it’s another option you can look into.