Yeah man the impact of running will deteriorate the cartilage in your knees as well as stress/weaken the tendons around it. As you age you're also enjoying a loss of regenerative hormones like GH/IGF-1.
Use the stair climber or an elliptical.
I'd also recommend looking into Prolotherapy. It's a non invasive technique (multiple shots of a natural sugar-based solution) used to cause inflammation and damage in targeted areas.
Some doctors will say it is "controversial" because they want to sell you something else or don't believe in natural approaches like this. It is cheap (around $75 bucks for a treatment) because all it is is simple shots.
The inflammation causes a cascading effect of the bodies natural healing abilities and allows your muscles/tendons/cartilage to re-repair itself - stronger and tighter.
I've done one session on my shoulder 2 months ago and it has practically eliminated the aching I would get from resting on it or lifting. I seriously was plagued with that shit daily. I'm going to go back for 1 more just to make sure its all gone.
www.prolotherapy.org
http://www.prolotherapy.org/regenerates-cartilage.asp (specific to cartilage)
Hope that helps!