Linn tabel won't stay on 45 slips to 33

Any linn owners know how to solve this problem I have a linn basik tabel with an akito 2 arm it was just recently gone  through and completely  tuned up it has recently started to slip off of the 45 spot on the spindel and goes right back to 33 every  time dose anyone know how I can solve this problem  so I can play my 45's as well thank you Michael