Tranny Problem - Synchros, Clutch, or...?

[JasonC302]

I am a total amateur when it comes to manual trannies, so please bear with me.

Recently, my stock 89 GT has developed issues shifting. Basically, on random gears and at random times, I will not be able to get the shifter in gear. When this happens it usually takes 2 or 3 tries to get it in properly. There is NO audible grinding occuring, the shifter is just blocked from going into gear. It occurs I'd say around 30% of the time, from 1st - 4th. Sometimes I can run through the gears just fine. Other times they all give me an issue. 5th is the only gear that doesn't seem to give me a problem. It also happens when I'm sitting perfectly still with the engine running at idle and I shift through the gears to test it out.

I know that my clutch cable has been out of adjustment for a while. I need to push the pedal almost all of the way to the floor to get it to engage. The auto adjuster is long dead. Could it just be further out of adjustment than usual, or might I have a synchro issue?

Thanks for the help!