Help needed for Reel to Reel tape deck

Recently after 14 years, I've taken out my Akai GX-4000D reel tape deck to play some old reel tapes and I am having trouble remembering how to change speeds to 7 1/2 IPS. There's a thingamabob that I do remember being concealed near the heads, which I have, but doesn't seem to help. Of course, I do have the owner's manual, but have turned the house upside down trying to find it with absolutely no luck. Frustrated, I checked the Alta Vista search engine typing Akai GX-4000D and found this site, but no posts to the old question asked remain. Any help would be greatly appreciate and I can be emailed at: Thank you! R.G.
Hi. You have to put a sleeve on the capstan.This sleeve is next to the heads cover.Then you screw this sleeve with a round nut that is the same diameter.This nut hold the sleeve when you use the 3.75 ips.Hope this will help.
i dont realy know lid akai in compton, ca stil services these decks but its worth a shot. chances are the sleeve is lost but a long time ago i got a sleeve for a different akai with the brand-roberts form them. maybe the sleeve is still on your deck, hope so. also, some of them had a speed switch that inableld 4 spds, slow yielded 1.37 + 3.75, the high spd yielded 7.5 + 15ips. good luck.