It won't help you now but you should NEVER issue final payment to a contractor until you have signed off on every detail of the job. In fact, in commercial contracting it is standard to withhold 5% as what is called "retention" until the punch list (final inspection) has cleared to the owner's satisfaction.
However, you do have some options. I would send a registered letter to the original contractor with a description of the problem and photos of the unfinished work. State a specific time frame by which you expect him to arrange to have the repair made (an exact date, say 2 weeks from the date you mailed it.) Tell him that if the work is not completed by that date that you will seek remedial action either by bringing a small claim against him, involving a mediator or by hiring someone else to complete the work and sending him a bill for it (it would be a good idea to get an estimate on finishing the work if you can.)
Honey gets you more flies than vinegar, so be as nice as you can in the letter -- tell him you really appreciate how beautifully the job came out and would like to be able to give him a recommendation for other potential customers but you hate for this minor annoying unfinished work to leave a bad taste in your mouth (say this even if you don't mean it -- if the guy thinks you will be p1ssed at him even once he has completed the work, he will be less likely to act.) You could take the same approach with the cabinet company -- tell them people have admired your new kitchen and it is embarassing to have them notice the missing parts and it doesn't reflect well on them. Ask what YOU can do to make getting this done more convenient.
You have to hit a middle ground between b1tching and being too lenient. If you complain too much, contractors will just ignore you. If you don't persevere enough, they will let you slide. Putting it in writing not only shows that you are serious, it also puts something solid on the contractor's desk so he can just hand it to one of his crews and say "Can you guys swing by and wrap this up tomorrow on your way back to the shop?" Chances are no-one remembers exactly what is missing and needs to be done. A well presented reminder may prompt them to finish it up, especially if they know it may avoid a legal hassle.
30 years in the construction business (and dealing with plenty of contractors and subcontractors.)