To replace the input shaft seal is not a big job Marmota but will take 2 or 3 hours to gain access, drain the BB, do the seal change, fill the BB with oil and put everything back. You do need to plan the job as it requires a few special tools, the gag to hold the flange and some large sockets for the shaft nut and to push the new seal in with. You could do this in your apartments underground parking area but, like most jobs, it would be much easier in a well equipped workshop. No fingers should be lost
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