AKAI GX-77 is a great machine. It has a great look, compact size and includes some interesting features such as auto-reverse function, manual biasing plus it uses the well known GX heads.
But there is a known issue with this machine related with the tape transport system, known as the "slow" fast-forward and fast-rewind issue.
There are several posts on the internet about this. Most of the posts placed in related foruns are innacurate or even totally wrong. Some people say that the problem is related with the blue 3W resistor in the spool motor boards, some say that it is necessary to replace the motor driving transistors, the driving belts, etc...
None of this is true and you will not need to replace any components (unless the belts are broken or too much loose, of course!). These are the main reasons for the "slow" FFWD/FRWD issue in this machine:
1- The transport path is a little bit complicated, because of the vertical loading roller mechanism that pushes the tape up against the heads. It was an interesting solution developed by AKAI engineers to save space with this vertical loading/unloading mechanism thus allowing the machine to be the most compact it could be. But, since the optical tape counter is attached to the roller in this same mechanism, when you use FFWD/FRWD functions, tape must continue "loaded" by this same mechanism in order to the tape counter to measure the tape travelling amount. So, when FFWD/FRWD functions are used, tape continues to travel through the same transport path as when the PLAY function is selected. Tape is then detached from the two pinch rollers but continues passing through the 6 heads and all of the "PLAY" transport path. Because of the high tape speed, this causes a lot of inertia within the tape path.
Well, i think that this is a design flaw. When in FFWD/FRWD modes the tape should be detached from the heads assembly (as it is from the pinch rollers) thus eliminatting a lot of inertia and increasing the spooling speed. Another benefit would be that the heads would suffer significantly less erosion caused by the tape at high speeds...
2 - Another problem is related with the spool motors itself. This motors are not the strongest ones in the world, so, when the take up loading tape spool is almost fully loaded and heavy, the FFWD/FRWD speed tends to slow down too much and some times it can even stop. Things get even worse when you use backcoated (thicker) tape types.
3 - We are talking about a machine that has almost 40 years old, in average, and we know that this machines where for several years or even decades in some shelf, not working at all, so, it is a natural thing that all the lubed mechanical parts got kind of "frozen". Lube grease present on these parts tend to get sticky with age wich will add friction and inertia to the system. Problem is that to eficiently replace or remove that old grease by new one you would need to almost dismantle the machine as it is so compact and complicated - and no one wants that, really...
You can try to re-lube some main and accessible parts, but you should be very carefull with that, otherwise you can damage electronic parts definitely.
If you want to do that, please never, never use spray lube such as WD40 or other similar product. It will do much harm than good to your machine. You should use apropriate lubing grease for electronics or you can apply a bit of sewing machine oil with a syringe with needle. Always take care to not applying in excess...
4 - Dirt in the several tape transport path components adds inertia to tape travelling. You should take special care with the "sticky sindrome" old tapes and regularly make a good cleanning of all of the tape transport path parts with isopropyl alcohol, specially the heads and the pinch rollers rubber.
Well, I came up facing this same problem sometime ago when i purchased a used GX-77 on ebay...
After taking care of it and done a good cleanning of all the transport tape path, the machine was working fine in PLAY mode in both directions, except when i used the FFWD/FRWD functions - the spools just runned to much slowly and almost stopped when the take up spool was almost fully loaded and heavy.
So, i started looking for a solution for the problem. And that is the purpose of the material you will find in here.