If your trem arm swings too loosely, I have the answer. - ve
I have seen a thread about this ages ago but I wasn't arsed finding it again but here goes anyway:
If your trem arm swings too loosely in the trem I found if you remove the bushings and paint the routed area (the indentations in the metal on the edge and lo pro edge trem arms) with yacht varnish, let it dry and then put the busings back on, your trem arm will remain solidly in place for 3-4 weeks at a time.
THis technique saves serious cash. Those plastic 'things' cost £1 pound here in Ireland *$1.22!!!