Tevo Flash stops extruding after a retraction : cant use retraction

I have a Tevo Flash Dual Z TouchBL standard. The printer stopped extruding after it did a filament retraction to move printing from one place to another, the wheel spins back to retract and then seems to get stuck, but the print process keeps on going. I paused the print and then restart it and it extrudes again and then stops on the next retraction. I tried printing without retraction and it prints the object. I tried it with the latest versions of Repetier and Cura. I tried it with a 6 mm retraction and retraction speed of 25mm/s, PLA at 200 oC and 180 oC .How do I make it print with retraction settings?

I have managed to fix the problem. I first changed the by changing the retraction distance to 2 mm and speed to 10 mm/s. It then started to work properly. I am now using a retraction distance of 4 mm and speed of 15 mm, no stringing at these settings so I'm happy . I have not tested it back to the original settings of 6.5 mm and 25 mm/s (whilst it works I will not fiddle with it!). I am not sure if it was the setting change that did it (can't do 6.5 mm and 25 mm/s) , or some how playing with the settings fixed something (unjammed a cog?) and it can work at full functionality? It works for now and I keep those settings, unless otherwise advised.