Why do you think that changing the ATF weekly is somehow keeping your dying transmisison running? If it is already worn out (which would not be surprising based on the miles--although that is impressive) how is constantly replacing the fluid helping? Also, if you are using the proper fluid (MB synthetic) you have probably paid more for fluid, gaskets, filters and such over the past year than the cost of a new transmisison! If you are not changing the filter by dropping the pan, and just doing a pump out, all you are doing is wasting time and money, as the magnet and filter are still going to be loaded with metal. Since the fluid never gets old enough to get bad, your changes serve to only drain your wallet.