If you have ever had to reach up and replace a tuner tube in a very restricted area, you know what a PITA this is.
Be VERY gentle reinserting the tubes.
After you have tested them be certain the pins are TOTALLY straight.
If they are not, it is very difficult to get them into the pin socket.
Now, if you are having difficulty getting the keyway aligned- Step back and take 5.
I have seen a number of cases where the tech(?) went ape and actually pushed the tube pins through the solid keyway area, making another hole.
This virtually guarantees that you will have to remove the tuner and try to get the pins on the tube properly aligned, or you might even- horrors of horrors- have to disassemble the tuner, replace the socket and re-align the tuner.
NOT a job for the faint hearted.
This mostly seems to occur on the phenolic wafer type sockets. I have never seen it happen on the Bakelite, ceramic, or micarta ones.
I only ran across this happening on chassis tubes a few times in all my years of servicing.
Also take care inserting Compactron tubes as it is very easy to bend a pin, and I have seen where Magnoval (The large 9 pin tubes with the thick pins); have been forced into the wrong socket destroying the standard large 9 pin Compactron socket.