The key question is, I think: **Is the stickiness caused by dirt/grime or corrosion/breakage?** In either case, I believe the answer is *yes, it can be serviced*, but in the former you just need disassembly and cleaning while the latter may require replacement parts, which are perhaps tricky to find (but check eBay).

If it's just the head that's not working, you can probably replace that part and keep the legs.