The laser seems to not be on proper focus as it moves towards the right side of the work space. 

I have done a cut test after realizing there might be an issue. Uniform thickness material wasn't cutting all the way through in the right side area of the cutting bed.

The photo shows it clear that the laser can't penetrate the wood towards the right side of the bed and it appears that the reason might be the laser loosing focus towards the right side of the bed.

A procedure to fix the problem is much appreciated.