I've a chattering issue with my 110 200tdi, doesn't seem to be the engine. but I can't find a pattern to it. sometimes it's chatter free for a couple of days then it'll start up again. If it's going to, it will usually start about 3 miles into driving, going straight. Chatters while coasting though not as badly. Seems most prevalent in 4th gear at around 30-35 mph, but 5th can be similar. Doesn't do it below 30 mph. If I drive more than an hour it can disappear again. I've linked a vid with the sound, audible at 2:42 (in neutral), 3:33 (clutch depressed) and 4:50 (it's pretty constant, just can't hear it over engine noise in the recording) Any ideas?