Steering issues with Komatsu D21A-7

First dozier, new operator, retired and wanted to have fun on the farm. Just purchased D21A-7 and it runs great shows 2100 hours. Sprockets and bushings are worn out. Can this happen in this amount of hours? The problem is the steering. When we test drove the unit all worked well except a little weak in steering backing up to the right. After getting it home and operating a couple of hours it started responding slow when turning right in forward. Then started to respond very little in reverse either direction. Now will not hardly turn at all forward are reverse. Dumping the slip clutch will get a small amount of turn. Then it might start turning and can go full circle if needed. Does not appear to have been sitting up. If clutches were stuck it would not have operated correctly when first got on it to purchase, correct? Unit pulls strong and can bog down to stall if against large tree. Fluids are full and clean. Could filter be dirty? How can I check without pulling it apart? I was fixing to pull clutches but am tired and low on funds. I will need to rebuild undercarriage but want to see what is required to repair steering first. Hyd. seem to be in good shape, no leaks now (repaired 6-way control valve was leaking) Blade responds very smooth and fast so I feel hyd. pump is working correctly and no problems changing directions forward or reverse, just steering right and left. Note: viewing controls under the floor plate they seem to move equal amounts when moving joystick right to left in forward or reverse.I appreciate any help with this.