Kubota B20 clunk noise

[fishman002]

I have a B20 TLB with 900 hours on it. Yesterday I was using the FEL to push over some 10 foot holly bushes at a customers house. It was in soft soil so the wheels has a chance to slip if things got too rough. The next day I used the FEL to haul 32 yards of top soil. During this process I was turning sharply to the left with the bucket full of dirt and heard a metalic clunk one time in the area of the rear differential. After I finished working that day I noticed what felt like a bump at every rotation of the rear wheels. It felt like there was something large caught in the tread of the tire. Of course the wasn't anything, but it bumps / clunks once every revoluton of the rear tire. Any thoughts?

 

[art]

Were you using the diff lock a lot?

 

[fishman002]

Update. I ran the machine for 3 hours today (easy) diiging out bricks from an old sidewalk. I drove it on pavement at lunch slowly in 1st gear at low RPM and listened to the clunk / noise. The sound comes from the right side of the rear axle and at slower speeds it sounds like a squeek. It makes the noise and bumps every revolution of the right back tire. In answer to your question , I have never used the diff lock but the pedal sometimes is in the down position whick I think means it is on. I lifted the TBL off of the ground with the FEL and the outriggers and tried to engage the diff lock but i noticed no change in the tires. HWat should I see if it is engaged?