When I first received my BRNO TAU-7 I did a thorough cleaning of the internal CO2 reservoir and all metal parts. I used a paper towel to wipe all the preserving gunk out of the reservoir. I twisted the towel up and made a carrot shape to fit into the reservoir.  After a few tries the gun was pretty much clean from factory lubes. I then applied a few drops of Pellgunoil to a cotton patch and used a .22 caliber cleaning rod (nylon tip) to apply a very thin coating of Pellgunoil to the gun's internal reaservoir. 

I loosened the forearm screw and slid the forearm forward to access the velocity adjustment screw and hammer spring. A drop of Pellgunoil was applied to both parts and also the hammer spring guide rod. The forearm was then replaced.  

The most critical lube point is the breech latch (loading gate). The breech pivot pins on either side should receive a periodic drop of lube to keep friction minimal. I use a mixture of Crosman Pellgunoil and Beeman M2M moly paste. I mix about two drops of each on a plastic surface and apply to pivots. The moly seems a bit too thick to use by itself. I have also tried mixing some GunSlick graphite grease with Pellgunoil and had good results but I prefer the moly. Even straight Pellgunoil will work if you have no moly.

The breech locking pin needs lube so it will enter the recess in the frame with reduced friction. With proper lubrication it will get deeper into the recess and secure better. I use the Pellgunoil/Moly mixture and try and work it around the pin and then cycle the pin in/out to move it around. I then apply a smear of moly paste into the frame recess. My locking pin now moves very smoothly.

When charging the TAU-7 with CO2 I apply a drop of Pellgunoil to the end of the powerlet which is inserted first. When using bulk CO2 I apply a drop to the valve pin on the gun's bulk fill end cap. One drop every second filling (or 2nd powerlet) is enough. If you try and use regular household oils you will likely get leakage at the gun's internal valve and seal damage can occur. I once tried an airtool oil and leakage occurred. I had to disassemble the gun and clean all the oil out with q-tips before it would stop leaking. A lesson well learned.

Changing seals on the TAU-7 is a very easy task. The two breech seals on the loading latch are the simplest to remove and they can be popped out with a fingernail or a stiff plastic probe (make something). These seals are simple o-rings and a finger push will insert the new ones.

The gun's internal seals require removal of the grip. With the end cap removed from the CO2 reservoir you can use the tubular wrench to unscrew the metal ring which secures the grip. This is usually very tight from the factory. Make sure you use the correct end of the wrench to remove the ring. Once the grip is removed the end plug at the rear of the frame can be removed to access the valve parts. On the end plug there is a rubber o-ring. 

Once the end plug is removed you can pull out the valve return spring and valve stem. If you look into the valve area you will see a white valve seal secured into the frame. This seal should not be touched unless it needs replacing. To remove this seal you use a long screw and carefully thread a couple turns into the seal to pull it out. Damage to the seal is inevitable. To insert a new white seal I used a ballpoint pen. The seal is placed on the end of the pen and pushed into place.

The bulk fill end cap has 3 seals. By removing the C clasp the two internal seals can be accessed. The 3rd seal is in the end and seals around the transfer bottle nib.

My TAU-7 is over a year old now and I am still using the original seals. I once replaced the white internal seal on a friend's TAU-7 which was quite old. He bought his gun around 1990 and it still works perfectly.