clunk clunk clunk

[cr10s pro woes]

Hello all, only recently did I buy a cr 10s pro and had around 100 hours of successful printing, well, with just a few issues, mostly due to ignorance. The problem I'm having right now, and for the last few days is that around 50 per cent into a 10 hour print, I get a clunking noise and the filament jams up at the cold end leaving a curly bit of filament at the beginning of the bowden tube, I don't think it's blockage at the hot end because if I pull out the filament and refeed everything is ok again for a few hours, then, clunk clunk clunk and another jam. The quality of the print until this happens is very good

I'm printing pla
nozzle temp 207
print speed 40, 20 for the brim
bed temp 60

layer height 0.15
retraction settings. minimum travel 3
Enable Combing. All
minimum extrusion before retracting. 0
z-hop when retracting. 0.075

retraction speed is 40, distance is 3.

The slicer software I',m using currently is the creality slicer 1.2.2 that came with the printer but I'm thinking of installing simplify 3d. Has anyone had experience of this problem? And would it be advisable to use simplified 3d with the cr 10s pro rather than the native slicer?

thanks