Anyone experienced with servicing suspension?

I just dug out my old MTB, and the preload/damper knob is jammed so i cannot adjust. Its made of plastic so if I force it it will break.

I also feel I need to service it in some way, perhaps put some grease in it.

Could someone help me with these things and give it a check over, as I want to go riding and dont want it to fall apart when doing so.

Thanks.

What fork is it?

just had my pace forks renovated by pace themselves .. i would recommend sending them away if they are decent quality
they've come back feeling much more fluid much more solid and they gave them a nice clean up, they adjusted the springs for my weight and freed up the knobs
as for doing it myself i wouldn't really know where to start there must be some guides on the internet to show you how to take it all apart and where to add fluids / air / grease

Just something cheapish and old school.

2001 manitou magnum R

I found a service manual but it is rather unhelpful;

http://spoke-n-word-cycles.com/TechnicalDocuments/Manitou/Manitou%202001/Manitou%202001%20Magnum%20Service%20Manual.pdf

Mtb forks really are cake to service...the manuals make them look complex but there is really nothing to them..i rescued a set of 2001 z1 zokes last sunday and had them apart in 15 minutes....use a manual and be methodical and fork services are easy...

p.s

Manipoo

Take it to a shop.

back from trip, forks held up ok although I really could've done with much less preload than the max it was locked too. Still had fun, mountain biking is ace.