Need Help! Chinese 40w down on power- where to look?

Have a 40w Chinese laser that is a little over a year old. Has had a decent amount of use, but not a heck of a lot- maybe about 3-4 months worth. I just fired it up again recently for some work and it just doesn't have the output it used to have and I'm not sure where to look. I have some 1/8 birch here that I would normally cut at just shy of full power and 10mm/sec in one pass and now it takes 3 passes at full power and no faster than 8mm/sec to cut the same wood. Tried to cut some 1/4, which I have cut before in several passes and after 15 passes, it still wasn't fully cut.

I cleaned the mirrors and lens and have double checked the alignment again and all is well there. Looking at the power meter, I am getting about 24mah on high, which I believe is about where it always reads. Only thing that seemed out of the ordinary is when using tape to check alignment and giving the laser a quick shot, it seemed the beam was leaving two burns a little over 1/16" apart, not one solid oval. I don't remember this from before.

Anyway, sorry this is so long, I just wanted to give as much info as possible. Any tips on where to look would be greatly appreciated. I was thinking of just replacing the lens and mirrors for the hell of it to see if it changed any but figured I'd ask first. How long does a lens typically last? Thanks in advance.
Joe