1990 JD 490D makes a growl/chatter/metal-on-metal noise - only in low range though???

Greetings - my otherwise pristine (rebuilt undercarriage on a 10k hour) 490D was working great and quiet. Just 10 hours ago she growls in turtle, but is silent in rabbit. In either low or high drive it seems to function fine.



Might this be a matter of something stuck in the one valve, causing it to 'chatter'??



Okay to use it until it becomes more defined of a noise?



Thanks for your thoughts!



~ Mark

1990 JD 490D makes a growl/chatter/metal-on-metal noise - only in low range though???