Really pleased with my Benchy.
just created my next print and went to change filaments (from Benchy Red to white)
It wouldn't move so I heated Hotend 1 to 200 as per benchy released the cam on the feed and pulled it nearly came out but then got stuck.
I also noted that there are now striations on the red filament I pulled back.
Could someone tell me what the correct process is for changing filaments?
My personal process for changing filament is to heat up the hotend, pull the filament a few CM then push back in slightly and then quickly pull back out which causes the end to stretch into a point rather than leaving a blob.
If you do get a blob and it gets stuck at the coupling then simply remove the ptfe tubing from the coupling, snip away the blob and pull the filament out as normal and then re-attach the tubing.
There are a number of small factors that can cause the filament to get stuck when trying to remove it. You definitely can't remove the filament while it's cold, so always heat it up to printing temperature first. The biggest one is probably letting the filament cool down in the hotend/nozzle for a while and then later heating it up and trying to remove it. The coupler for the extruder to PTFE tube has very little tolerance beyond the 1.75mm filament width, so the 'blob' that builds on the end inside the nozzle can get stuck there if it's too hard and doesn't deform into the tube when retracting. I've also had problems with there being too much blobbing when the bowden tube wasn't flush with the nozzle and there was a bit of build up. Not sure if replacing that coupler with a slightly wider ID one would cause more harm than good though, hopefully @Makertech can chime in there.
I usually let the hotend sit at the upper end of the temperature range(215 for my PLA) for a minute before I retract the filament. If it still gets stuck at the end, just release the PTFE tube at the extruder side and clip off the thicker blob. Alternatively if you don't mind wasting the entire length of filament that's inside the bowden tube, you can just clip the filament at the extruder and carefully load a new colour in through the extruder and into the bowden tube. Either method you use, just keep extruding after the new filament is loaded until you see the new colour cleanly extruding and you should be good to go.
The grooves/striations you see on the filament are likely normal, the extruder gear has to dig into the filament in order to get it to move forwards/backwards.