I have a job with a mixer tap in a kitchen which is leaking from where the spout joins the main body. The last company I worked for just insisted on replacing the whole tap in this sort of thing but can it be fixed? Obviously it doesn't just 'unscrew' but I assumed that maybe there is a screw/allen key on the back if the tap body and then a washer inside. Am I right or was my old company right? Thanks.