Dewalt DW300 Jigsaw not cutting square

[al19]

My Dewalt jigsaw which is about a year old no longer cuts square. I use it on soft wood on a 5 speed setting and position 0. It cuts perfectly straight but the cut is not square. I've checked that the shoe is set to 0 and I'm using a new blade. I can't seem to get a 90 degree cut. 

 

Any ideas?

 

Thanks