Using good quality filament and taking care of your machine, it should run faithfully. Below are a few tips for properly maintaining your Ultimaker.
Axes Rods--X, Y, and Z
The printhead and heated bed ride on eight shafts. In order to help ensure ease of movement, make sure that the rods do not acquire dust or debris. Generally, it starts to become noticeable on the ends of the shafts, as pictured here.
If the shafts are dusty or dirty, wipe them down with a paper towel or cloth. After wiping them down, or if you start to notice resistance when moving the printhead or bed, add a couple of drops of light machine oil to the rods. Sewing machine oil works well for this. Move the head around by hand to spread the oil on the printhead shafts and axis rods. To spread the oil around on the Z-shafts that the bed rides on, put a couple drops of oil at the top of the shafts, and use the printer menu to raise and lower the bed. Go to Maintenance —> Advanced —> Raise Bed. This option will lower the bed to the endstop and then raise it up again. Repeat this several times.
If you start to notice horizontal bulges on your prints or start to see debris building up on your Z-screw, it may be time to clean it. Use rubbing alcohol and a cloth (a paper towel will shred) to clean the threads of the Z-screw. There is not need to disassemble the printer. Use the green grease supplied with the printer to lubricate the screw afterward by applying a line of it up the Z-screw. Use the Raise Build Plate option in the MAINTENANCE->ADVANCED menu to spread the grease out over the screw.
Over time, the bowden tube can experience wear and tear, especially if you’re using more abrasive filaments. Your bowden tube should be good for months, but if you start to experience trouble feeding, it’s worth taking a look at your bowden tube to check for any sign of damage. The feeder end of the bowden tube should be slightly widened out to help facilitate feeding material. The printhead end should be flat, and should be fully seated in the white PTFE coupler in the printhead. Sometimes, when you remove it and replace it, it can get caught on the metal plate above. This will give you feeding problems, so if you’ve removed it for any reason, please check for proper seating. If you’re not sure if the bowden tube is still in good condition, remove both ends from the printer by sliding the blue clips out, and pushing down on the white collet while you pull the tube out. Slide a fresh piece of filament through the tube by hand and check for any point of resistance. When the printer is not in use, keep the printhead in the front right corner to put the minimum amount of strain on the bowden tube.
ABS has a tendency to grind during printing. It may do this while printing perfectly well. If you are using ABS, check the feeder and bowden tube for signs of ground up filament. It can be carried up the tube and clog the printhead. To clear it out, remove the bowden tube from both ends of the printer. Use canned air to clear out debris in the feeder. You can insert a small piece of paper towel into the end of the bowden tube, and push it through by hand with a piece of filament. It should gather up any debris and force it out.
The PTFE coupler is the piece most likely to experience wear and tear and need regular replacing. Much like the tires on your car, it will deform over time and exposure to the elements—mostly heat. Using PLA and other non-abrasive low temperature filaments (210-230 C) the PTFE coupler should be good for about 500 print hours. You can check the number of print hours on your machine by going to Maintenance —> Advanced —> Runtime. It will show you the total number of hours printed, total number of hours on, and meters of material used. With a high temperature or abrasive filament (for example ABS, CPE), the PTFE piece will probably wear out sooner. Don’t worry about replacing it unless you start to see a decline in print quality. Some indicators that it may be time to replace it: problems with retraction or a bulge at the end of the filament when you go to change material.
If the coupler is deformed, it’s usually wider at the bottom where it’s been exposed to heat. It may also be discolored due to the heat. Below is a photo of two particularly bad couplers beside a new coupler for comparison.