After finishing yesterdays gorrick I noticed my reba sl's were making a wheezing/squiding sound on compression, and looking down there was a reasonable amount of oil around the gate valve/compression dial.

It still seemed to lock out ok and work fine just a bit noiser than before. I've cleaned the oil off to see if any more leaks over night

Should I be concerned? I could really do with out sending them off for a service…

It'll only be a rubber seal at worst. It's really very simple to check yourself, you might even get away with just a quick clean out of the threads, but it might be the centre seal. Impossible to say without looking at it….

I imagine it is easy if you know what your looking for! I've never opened up a set of forks so a bit nervous about doing ruining them.

Will the seal be obviously deformed or something?

New Rebas? If so it's expected. If they're not, send them off or fix them yourself like PP said. Mine died about a year ago and Merlin sorted them for me for a VERY reasonable price.

Got them April 2008 so not that new, but they haven't had too much of a hard life as I've got a few bikes. Sounds like I might have to do a bit of fettling then.

If I just leave it and it is a blown seal is it likely to cause any proper damage or just continue to leak?

To be honest, at that age, they need a full service. Do it properly and they'll last forever, do't do it and they'll be knackered next year. It's worth spending the money sending them off to TFTuned to be done properly, the first time at least, because they'll resize the bushes at the same time, which you cannot do yourself….

Otherwise, they are stupidly simple to open up yourself for basic servicing in the future.

Heve a look at these I knocked together –
(Not specifically servicing, but it shows how simple they are to get apart)

https://docs.google.com/fileview?id=0B1AoGIWBz4H1YWNhYWRkODYtNzRiNi00YTA1LTlmMjctNmQzOWQwMDdiZGFl&hl=en

https://docs.google.com/fileview?id=0B1AoGIWBz4H1M2E5ZTc0MTItNjM4NS00YjBiLWEwZDgtMjEyYTQ5NWZlMjc5&hl=en

Ok thanks PP – I'll take a look at the guides. Ideally I'd get them serviced but money's a bit tight at the moment.