ok, so after a few glasses of gin and some more checks on the printer, I took the heater assembly apart and it turns out that my PTFE tube is melted at the tip where the extruder is, and there is a hole half way down.

Firstly, I'm a complete n00b to printing, my printer has 550 hrs logged on it and its been running pretty much 24/7 since I bought it. For those who dont know, filament isn't the only consumable on a Flashforge printer! To protect the cooling tube and/or the extruder parts, there is a non-stick PTFE plastic liner that runs up from the nozzle to the stepper motor gear. This needs replacing every so often apparently!

I don't know if this tube exists on other models of printer, but it seems like a common replacement or upgrade for people is to replace this with a completely metal one, Micro Swiss seems to be a popular supplier when I stumbled across some YouTube videos for taking apart the hot end.

So my tube looked like this;
IMG_1872.jpg

I'd appreciate it if anyone could tell me what could have caused this hole in the middle, as that is likely the root cause. Knowing the fix is good, but knowing how to stop it being a problem is better!

Also, if anyone has any other tips, or something that may seem completely simple, I'd love to hear it as I am learning as I go along. Spending a week on this issue has actually taught me a lot about 3D printers and in a broad sense how they work. Maybe starting off with a kit would have been better than a completely assembled printer so that I could get familiar with these things up front.