The 709 is quite different from a Glock. The restrike (aka double action) trigger is part of the trigger bar, just like Glock, but the 709 striker is not preloaded (partially cocked) like Glock. Glock has nothing that resembles the 709 single action trigger/sear. My advice is to smooth out your SA trigger by dry-firing the gun after a good cleaning and lube of the sear area. The actual surfaces where the sear rides in the MIM aft bracket are not really accessible for polishing anyway. Furthermore, you are likely to lose parts if you disassemble this mechanism and Taurus will not sell you replacement parts (all restricted). If you do decide to disassemble this area, do it inside a big plastic bag or in a bare, closed room where nothing can get lost. Reinstalling the sear spring requires either a special tool, a third hand, or a DIY trick (I used a loop of dental floss).
Seriously, you can clean this area very well with GunScrubber. I use compressed air to blow out residual Gunscrubber and dry things out. You MUST relubricate after using Gunscrubber. I use spray lube here, again followed by compressed air. The only reason to disassemble the sear assembly , IMO, is if you have a bad part or need to adjust the sear spring. Since you can't get replacement parts, you can't fix a bad part. If the sear sometimes fails to catch the striker or the SA trigger force is very erratic, the sear spring force could be too weak; so the only reason to disassemble the sear assembly would be to adjust the sear spring force, IMO.