Hi guys so I had a similar problem couple of weeks back and applied and did some re adjustments to my laser as recommended but I still keep begetting this indentation on my work normally same place …any advice please
Similar to what? 
In any case, that looks likely mechanical to me. Do you hear a “clunk” of some sort when it happens?
What kind of laser do you have?
Not really it seems specially to do this on circular designs… or larger designs… its an atomstack A5
You didn’t answer the question about what it was similar to, but you maybe meant similar to your earlier post?
You didn’t say in that post whether the advice helped, nor answer all the questions in that thread. 
Both of these look mechanical to me.
If it weren’t happening in the same place, I’d also consider loose wiring, but if it’s happening in the same place, it’s probably some mechanical problem.
You can try moving the gantry by hand (not too fast) and feeling for any hesitation in the movement, listening for any difference in the sound. This could be something as simple as a piece of something adhesive stuck in the extrusion.
It’s also possible that when you tightened the belts (in the previous post) that you got the gantry not perfectly square to the frame, and/or possibly the frame isn’t perfectly square.
This is very unlikely to be a software problem.
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I didn’t realise that was aimed at me …but yes I did say on it the one I put on here a couple of weeks ago…
Might be a bad spot in the belt allowing a double pass at that particular point. Maybe because you tightened the belt too much and stretched it at the joint (where the belt is welded together). Just a guess
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Looks like they Y axis motor is skipping a step or two. If this happens at the same position on the work area then it’s something in the motion system(belts or rails, etc) and if not then it could be a bearing hanging up either in the linear rail system or in the stepper motor. I’ve had to rebuild a stepper motor on my K40 when a bearing started hanging up and was no longer rotating smoothly.
Ahh ok thank u for that 