Suggestions how to repair these


I have a pair of JPW Powered Monitors (1995), Made in UK, perhaps in one of the last production batches before the company was acquired and moved production in the Far East. Bought brand new for a PC-based audio back then but used it intermittently for couple of years only and stored them for several years in its box. Took them out recently and I'm still amazed at their soundstaging and imaging particularly if mated with a sub. I really like them a lot. However, a couple of things need to be fixed.

1) The volume pots are stuck at 9 and 10 o'clock positions and don't move at all. For now, however, I'm using the source's volume control but eventually I'd like the source at full volume and adjust the speaker's volume controls. What caused it to get stuck? Is this a common occurence when left unused for long periods? Is this something I can repair myself or should I just bring them to a qualified technician? What needs to be replaced here (or cleaned)?

2) White spots/residue (not dust) have developed around the baffle and cone areas. There's no effect whatsoever on the sound but I'd like to remove and clean them. Can you suggest the best and safest way to do this? Any specific cleanning material?

For visual reference, please take a look.

Everything else are perfect - cabinet, grills, etc. are spotless and clean like new. Sound quality, as mentioned, is spectacular. But these two things bother me and would like them fixed. Any helpful suggestion or recommendation would be greatly appreciated. Thanks.
edgejazz
Thank you, Mcfarland and Mr.M. I think I can handle the cleaning and that sort and if it doesn't work will send to a technician for replacement.
If they're stuck, I would spray them lightly with a tiny amount of silicone based lubricant first before I got out the contact spray, especially if the shafts of the pots are plastic. Many plastic shafted potentiometers will literally melt from exposure to certain types of solvents, especially those used in spray contact cleaners. Plastic shafted (and conductive plastic element) potentiometers are best cleaned and lubricated with Caig MCL, a goopy blue spray designed for the task. Either way, use way less of any type of spray than you initially think - a tiny little dab will do.

-Richard
Thank you, Richard. The shaft of the pots are metal but I'll try your suggestion too. I plan to work on it over the weekend.