HI your chain is mentioned in previous posts and there are u tube references also --there are many people who can diagnose and fix for you if it is your chain - I am sure you will get other references -you must replace the tensioners and slides and sprockets with a modified chain --what is modified I cannot tell however I had the job done by the country garage straffan and I have no problems so far -- the crankshaft is milled at the end as a gear as opposed to the century old practice of fitting a woodruffkey and gear which can be replaced with a new/ better / double row gear wheel ect --proper fix --but no----the EVERYTHING WE KNOW ABOUT THE CAR IN A CAR engineer is young-- about 9 years of age --not well at all at all--has been fed for some years now a quanity of white powder which as it turns out is not baby formula at all and not even Chinese baby powder which would have made sure all of us could drive with great joy the previous 5 series which did not have the cocaine Raleigh bike chain fitted to the rear of the engine --I could go on I should go on -- the bastards --bugs