I’ve got that old baseboard heating set up that is a pain to clean. You’ve got to pop off the front metal panel and then take the vacuum and vacuum out between the metal aluminum fins that surround the copper pipe, but even that usually doesn’t work. So you’ve almost got to use needle nose pliers to pull out the dust that’s accumulated between each fin. Such tedious work, but it really has a bearing on how well your heating system works.
Baseboard heaters work by using convection, cool air comes through the bottom of the unit ans is heated by the copper tubing and then aluminum fins and then exits as hot air out of the top. By blocking that airflow in any way you reduce the efficiency of the unit. So any amount of dust stuck in there can have an effect on your heating element.
So as much as it is a pain to clean, it is worth doing once a year. Take one room at a time and you’ll notice the difference.
It is also important to make sure that none of the aluminum fins are touching eachother – straighten them out for better efficiency.