I've had my .22 TF-89 for nearly 2 years and it's a great gun. I find mine is very hold-sensitive and doesn't like to be shot off a bench (solid support). If I keep my hand/fist under the forearm, then it shoots much better. Any slight difference in the way I shoot it and the groups open up. After about 5000 shots it broke the main spring. After a lube-tune and new spring, it's smoother than ever and seems to be a little more powerful and less hold-sensitive. Before the new spring it was shooting Hobby's at 900+ fps and H-Points at 840fps (summer). Before the new spring it was shooting the H-Points at 780fps at about 40* temperature. After the new spring it is shooting at 825fps at 40*. That should put the summer fps in the high 800's!!!!!!!!
I've tried nearly 25 different types of pellets through it. It seems to like all the RWS the best by far. I haven't had good luck with the Crossmans, Gamo's or any other brand. I personally shoot only the H-Points and have killed numerous birds out to 70 yards and squirrels at 50 yards. I just bought a tin of Super Points to see how they carry velocity at longer ranges compared to H-Points.
Soon after getting mine, I took apart the trigger and used a Dremel and sanding drum to smooth all surfaces that rub on each other and a file to square all edges that break contact. I also adjusted all three trigger screws and greased everything well. These things make my trigger the best out of all the guns I own.
I have the Leapers 4x32 scope and 3-bolt Accushot 1-piece mount on mine. I bought a better quality scope stop as well that has the two white plastic buttons on each end. After my recent rebuild, I noticed it had destroyed both white plastic buttons so I flipped it around. The scope hasn't moved but the recoil is destroying the front of the stop.
As mentioned before, loctite all three stock bolts. On a recent starling shooting spree a front stock screw had worked loose and I couldn't figure out why I wasn't hitting @#$%. When I got home I noticed it was very loose. Blue loctite should solve that.
I hope you enjoy your TF-89 as much as I have.
Doug