The A103 marking means that it's a logarithmic 10k Ohm slider.
To find a replacement, start by finding one with the right mechanical dimensions and pin placement - it will be available in 10k log since that a very common value and taper. Suppliers like TME, Digikey, RS, Farnell etc. have nice searchable product catalogues where you can specify many parameters of a part to find a match.
Or with some luck Arturia will drop by to give you an ALPS, Bourns or similar part number