Have a JD 170 lawn tractor. When turning the key, wometimes it would connect and sometimes not. Thought the issue was the starter, so had the starter rebuilt along with the solenoid. Thought I had taken care of the issue, it took right off. But next day it was back again. I took off the switch and noticed some corrosion..so I filed it off and used the electrical contact cleaner..once again it took off...but again it doesn't. It has me perplexed. Would appreciate any insight to this issue. Thanks