Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

I maintain a building and have to snowblow the walkways. They have an Airens 11528LE  drive problem and no manual with the machine.  I have taken the access plate off the bottom and can't figure out how this thing is supposed to work.  I had an old Airens with a knob on the side of the wheel that allowed you to switch from 1 to 2 wheel drive and this has a lever on the left handle that I had been pulling once and it would be in 1 wheel drive, I would pull it again and be in 2 wheel drive.  It worked all winter untill recently when it will most often stay in 1 wheel drive and occasionally slip in and out of 2 wheel drive.  I read in another post that I should adjust the barrel that is secured to the body in the rear where the cable goes through to have no slack.  I did this and I loose any 2 wheel drive altogether so I gave it a lot of slack and I still have no 2 wheel drive.  I started to adjust it turn buy turn (This took a bit of time) untill I reached a spot where I had some kind of 2 wheel drive but again it would slip in and out of 2 wheel also there was a lot of clicking going on when I would push the machine forward (no power or levers engaged) is this normal? Inside the access panel under the machine the lever cable is attached to the top of the left gear and a spring is attached on bottom of the right gear.  Thanks for any help you can give me.