Some people have tuning problems with this type of tremolo system. Here are a few things to check, and adjust, to improve tuning stability:
Make sure all the fixings are secure: The small screws on the rear of the tuners, the fixing nut on the head stock.
Most modern tuners have a small screw on the tuner tip. If the tuner feels very loose you can tighten the tuner tip screw to take up the slack in the tuner worm. Do not over tighten.....just finger tight.
Make sure the tremolo block is sitting at 90 degrees to the body. (See Tremolo System section for adjustment)
Each spring should be exactly the same length from the back of the tremolo block to the end of the spring itself. There is no need to have one spring tensioned more than the other. A simple tool for this is a plastic ruler cut down to a usable size to fit in the tremolo cavity.The ruler can then be laid on top of the spring to measure its length.
Check that the rollers move freely. If the rollers are stuck, for any reason, this could create some friction that might cause the tremolo not to return to it's zero position easily.
Remove any sticking rollers and clean out the slot. A tiny amount of Vaseline could be added to the axle ends to aid movement, but generally this is not necessary.
Make sure all the nut slots are wide enough to accept your string gauge. Make sure each string is able to move freely and are not sticking in the nut slots.
If, for example, you move to a heavier string gauge, the nut slots may not be wide enough to accept certain strings. In this case the nut slots must be widened. This can be done by carefully using folded Wet & Dry or sandpaper but if you are not confident then have this work carried out by a professional.
Make sure that the nut has not come loose. This is quite common. The nut can be glued back onto the guitar using Super Glue Gel or similar. If in doubt seek help from a professional.
I personally add a very small amount of Vaseline to the surface of the zero fret when I replace the strings to aid the movement of the strings during tremolo use. I add a small amount to the little finger and wipe it along the length of the zero fret and then fit the strings. It is totally optional and not necessarily needed.
Make sure that the neck fixing bolt is tight and also the two neck alignment screws inside the guitar.
Sometimes strings themselves can be a problem. I personally use Ernie Ball type strings. I have found it very useful to solder the wrap around part of the plain strings, having had some plain strings slipping at the ball end because the wrap around isn't as tight as it could be. Before fitting each plain string, heat up the wrap around, with the soldering iron, and add a small amount of solder.
Once cooled, the string can be fitted. This will prevent the wrap around from slipping and prevent tuning problems later.
I have worked on one or two Red Specials that had a tuning problem involving movement in the tremolo bolts.
The symptoms were that if the tremolo arm was pushed down and then released the guitar would return to pitch but if the arm was uplifted, even by only a small amount, the tuning was slightly sharp.
I traced the problem on these particular guitars to the tremolo bolts.
When the tremolo arm was uplifted (something that isn't generally used by Brian May fans as it is not in his regular style to uplift the tremolo) the tremolo bolts moved downwards towards the bottom of the tremolo cavity, moving the springs with them. When the tremolo arm was pushed downwards the bolts moved back to their original position.
Obviously the bolts were slightly loose in the threads of the bolt retainer inside the guitar.
To cure this problem I used a simple remedy. I wrapped the last inch (25.4mm) of the thread on each bolt with PTFE tape (plumbers tape) .
This tape will fill any gaps in the threads and, when refitting, the bolts will feel tighter to thread back in. I found that this stopped the movement of the bolts and tuning stability was restored.
Here is a description of what this tape is, for those who do not know:
This is the correct method to apply the tape to a thread:
Wrap the tape along the thread, from the end of the bolt, to approximately one inch along the length then begin to wrap the tape back towards the end of the bolt. This applies two layers of the tape. This should be sufficient. You can either cut or rip the tape when you have completed the wrapping. Rub your fingers over the tape to press it into the threads. Once this is completed, refit the bolts and set up your tremolo system.
Do not wrap the tape anti-clockwise as when you begin to thread the bolt back into the bolt retainer it will unwrap the PTFE tape.
If the bolts have to be removed at a later date, the PTFE tape will probably work loose. The tape will have to be replaced when refitting the bolts. If any tape remains in the bolt retainer, it can be carefully removed with the aid of a tooth pick or a sewing pin.