When we were looking for a drummer for a band I played in (in fact in two different bands) I used Musolist and had success finding several possible people including one who I currently play with. Standards of the players were really good. Might be worth a go.

The other place you might try is if you have a local folk/whatever type of music club with a newsletter. I live near York and the Black Swan Folk Club has a regular newsletter that reaches lots of musicians. I joined an Irish band after someone advertised that they wanted to play with others and that led on to meeting various other people I've been lucky enough to play with.

The other is to find suitable venues that play music you like and ask. In April this year I played at an open mic in a pub a friend recommended to me and got chatting to people after playing. I talked to one guy who I had seen play bass in a band locally and mentioned that I really missed playing live in a band. Coincidentally he wanted out of the band to go and join someone else but didn't want to let them down. Within a week I'd joined and by Xmas I'll have played about 25 gigs with them.

Networking I think they call it these days. Let people know you are interested and stuff happens.

Good luck.