Wasn't expecting the hotend to get clogged towards the end after @4hr printing
I have had the same issue, i have found even with the print nozzel, throat and blue PTFE tube all installed as far as possible and nice and tight. the blue ptfe tube gets pushed out of the crappy cheap hotend/bouden connector and the filament melts in the gap and eventully builds up enough to block.
Its happened to me two times now. Im thining about getting an actual E3D one and installing it on this as a temp whilst i use it to print the required parts for the one i want to build myself. true reprap style.
acetone bath to easy the clogged plastic. one of the nozzels was the first to block. the throat is also fully blocked. i assume this was pulled out of place during the filament changed during the dual print. failed at 95%
Print one of these:
There are several variations out there if that one doesn't fit. The black plastic piece can be pushed in by the movement of the print head which allows the bowden tube to slip. That clip prevents that from happening.
I see you have the same benchy imprints as I do (feel better that I wasn't the only one to do that). You may need to check your z-offset. If the nozzle is too low it cause excess pressure in the throat. @Rai
Another thing to check is your hot-end temperature. If it's too hot ... or left hot too long without printing ... it can burn the filament (turns a brownish color). Also, make sure the thermistor is all the way in so you're getting more accurate readings. @sebastian waters The stringing in your pic might indicate too much heat. See here:
Finally, when you remove the filament, be sure to heat up the tool (hot-end) first. That will prevent the filament from breaking inside the hot-end.
 Also, a heat gun is very effective for clearing out the larger bits. A hair drier might also work, but I haven't tried. Acetone is less effective on PLA. So I clean with heat 1st, then use acetone to clean any small bits caught in the threads.
@andrew leroy thanks for the tip. i did make this mistake during my first few prints but i did correct notice that and corrected it and that solved the serious stringig i was having at the start. i believe the stringing im seeing now is due to a small amount of filament still being in the nozel after the retraction. in the purge tower there is a centre coloumn which is used for wiping this string. maybe i havent enbled the wipe setting for both filaments I will have to check later. Im not using the printer anymore until my linear rails turn up and possible my new hotend as well.
Thanks for your comments guys, I'll try out your ideas, looks like it was too hot from your comments, there was this brown liquid buildup.I was trying out some custom settings at the same time. Temp at 215-210 °c rather than the usual lower 205-200. Or might have to change the hotend completely. The print bed is much knackered now. I was rushing to put a print job. Lessons learnt.