Infill missing near edges or is rough

I have a Prusa, Gen7, Pronterface, Slic3r and Marlin. This is happening now. Before when I ran Teacup I didn't have anything like this problem, infill was great. So I am assuming it is Marlin causing it. I have a feeling it might be something to do with the jerk settings but not sure and hoping someone here can shed some light on it?

Here is my config for acceleration and jerk

#define DEFAULT_AXIS_STEPS_PER_UNIT   {114.285,114.285,2560,725}  // default steps per unit for ultimaker 
#define DEFAULT_MAX_FEEDRATE          {75, 75, 4, 5}    // (mm/sec)    
#define DEFAULT_MAX_ACCELERATION      {1400,1400,400,10000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for skeinforge 40+, for older versions raise them a lot.

#define DEFAULT_ACCELERATION          1400    // X, Y, Z and E max acceleration in mm/s^2 for printing moves 
#define DEFAULT_RETRACT_ACCELERATION  1400   // X, Y, Z and E max acceleration in mm/s^2 for r retracts

// 
#define DEFAULT_XYJERK                6.0    // (mm/sec)
#define DEFAULT_ZJERK                 0.2     // (mm/sec)
#define DEFAULT_EJERK                 2.5    // (mm/sec)

Thanks!

Are your belts tight? Your circle looks well rounded so I guess they are.

Your extruder motor seems like a Minebea low-torque one (I can't really tell as only half motor is shown). You can try with 1000 as max acceleration to see if it helps.

A lower ejerk will not harm you, you can try 1.0

Your max feedrate for the extruder seems low, default Marlin value is 45.

Hi. Sorry about replying to this late but I have been away.

The extruder is a Greg's using a Nema17, it's 4.3:1 ratio.

Belts are tight, I have tensioners on them.

Is the mm/sec on the extruder for the input or output? As in, is it 5mm/sec of 3mm filament? Or 5mm/sec of 0.35mm extrude?

I've tried setting the ejerk to 1, also to 15 = no difference.
I upped the max feedrate on the extruder and it made no difference.
I tried setting the xyjerk to 5 and it helped a little bit.

If I print slower it is better but not as good as what Teacup firmware was there is still gaps that change in size between the infill lines.

Looking at it closely it looks as though when the infill gets to one side and changes direction to go back it leaves a good line up to the perimeter, then gets thick (over filled) while changing direction then when it accelerates off heading bac kto the other perimeter it goes blank as if the extruder isn't extruding (lagging behind) for about 2mm. This doesn't happen every time it gets to a perimeter but only about 30% of the times.

From this I gather it has something to do with the acceleration and jerk settings. But I don't know what. Unless it's the J-Head hotend that isn't keeping up?

You may well be answering yourself: any hotend has some speed limit. Going beyond that, will cause intermitent extrussion at best or complete blockage at worst.

You can use M220 command to slow-down an ongoing print to. let's say 50% of the speed. If at that the print goes ok, all your problem is that the hotend cannot cope with the speed you are trying to make it work at.

I have a J-Head Mk V-B. I thought these could go faster? At the moment print quality is lost after 60mm/sec on the X/Y axes. Pronterface doesn't show any drastic drops in temperature. Just +/- 4 degrees throughout the print.