That's incredibly good for only your third scroll saw project. Most people cut for years before they can follow pattern lines that well. The "Scroll Saw Village" www.scrollsawvillage.com
forum is the best place to learn the strengths and weaknesses of the DeWalt 788, and they have a list of all of the bearings and part numbers to buy them with. You don't (shouldn't) buy replacement bearings from DeWalt. You can get better bearings through bearing and power transmission specialty stores or on the internet. These stores can be found in larger cities across the country. You will likely pay less than half what DeWalt charges for the bearings, and you will get better quality bearings this way too.
The tiny bearings in the short arms that move the blade up and down are bearings with no internal race. Then you buy the internal race (sleeve) as a separate part number. I found that getting some synthetic grease and putting a tiny bit of this grease in the bearing hole with the flat end of a tooth pick, before inserting the sleeve and bolt, will make these bearings almost last forever. Do not use automotive grease. Do this on your first disassembly and you may not need to replace any of them, ever. While at it, look for wear marks on the sleeves and turn each sleeve 90 degrees from it's original orientation as you replace it. Bearings wear when there is inadequate grease between the moving parts. The synthetic grease does not dry out, so it continues to lubricate and move around within the bearing, keeping wear to an absolute minimum.
The bearing on the end of the motor shaft and those in the rocker near the motor that moves the long rods to control the blade motion are larger sealed bearings that take a hard beating. If you truly need to replace a bearing, it will more likely be one of these the first time that you service your saw. There are bearing numbers etched in the bearings to help find the correct replacement. The numbers indicate the size and type of bearing. Any bearing company that makes this size and type of bearing will use this same number for it. Buy one of the better quality brands and you will have a perfect replacement. The connecting rod between the motor shaft and the rocking vertical arm can stretch from prolonged hard use. DeWalt now sells this connecting rod complete with bearings all assembled because of this. The bearings require a small press to push them in or out of this rod. If they slide out easily without requiring a press, it's time for a new rod. It's aluminum and the bearing holes elongate from heavy use. The bolt that the rocker pivots on sometimes loosens or breaks, so I suggest that you consider finding a stainless bolt of the same size and style that matches it and replace it. Lowes has them. Consider using blue
Loctite on the threads to keep it from loosening in the future. The blue Loctite will still let you remove it the next time with a wrench. DO NOT USE
red or orange Loctite or you may never get it apart the next time.
If your saw is no longer running smoothly, I'm almost willing to bet that your problem is back in the connecting rod and rocker arm area near the motor. Bad bearings and loose bolts in this area are the main causes.
Take your time, and take pictures with your cell phone as you disassemble the saw. Watch the Gwinnet Woodworkers videos on Youtube and you should have no problem fixing up your saw. Join the Scroll Saw Village Forum and share your experiences and projects with the rest of us like minded scroll saw woodworkers.