Need M9990K Belts

Hi everyone-I just removed the main belt that goes from the motor and around the big flywheel and the tape counter belt.
The top 2 belts.
They measure 5.5" exactly but I'm thinking they will be slightly stretched.Would it be a 5" belt I'm wondering?
It wasn't to bad getting them off-just time consuming and somewhat tedious but then again I'm workking on the floor!
The main is slightly larger in diameter than the tape counter belt.
Any input on this would be great.
I'm determined to get this thing going.
I already lubed the motor and all shafts.
I temporarily used a smaller belt and it's kind of slow-I think it's because it's to small-straining the motor-or slowing it down.
I quit using the cassette as I don't want to wreck anything.

Has anyone done this model and what belts do I get?
Have a great one-GB.

Jeff. The M9990 takes 4 belts. They are:

SBL 5.4
SBO 7.0
SBO 10.5
SBT 10.0: If you cant find a SBT, you can use SBS -- it will work.

Sounds like you only replaced the 10.0 and 10.5 belts (remember, if you fold them together, it's doubled). The main belt is a little hard to see and it's below the Capstan flywheel. That is the hardest one to get to. I recommend a belt hook tool to do that one. Another thing to look for is a slipping drive clutch. That is the thing near the bottom that has a lever that presses against a pulley. If you disassemble it, you'll see that there is a felt clutch inside. If the clutch surface is glazed and/or the felt is worn, it could affect the operation. If everything else seems to be working properly, and you suspect that the reel is slipping, then you may need to resurface the clutch. Adding a few scuffs from 400 or 600 grit paper is usually enough to restore operation but don't overdo it or else it won't slip enough. This main belt is a very thick one. 5.4" large is the proper size but some folks have indicated a preference to go with smaller 5.3". You can even get by with a 5.1" belt but be careful and try to use the proper size belt as much as possible. While it's tempting to go with a smaller belt, the extra tension will eventually wear out the bearings and motor and motor mounts. Those SBL belts generate a tremendous amounf of tension if stretched even a little too much.

Thanks so much for that Norm!!
That makes sense as they would about 11" but at 5 1/4" times 2 = 10.5" & the other is 10".
These 2 I need for sure!
As far as the other belts I may get them too so I do the whole job.

Norm-1 question,That darn circuit board is kind of in the way-I have to keep one side propped up to work on this thing.It's not the easiest but it's do-able.
It's got soldered wires on both sides so removing to completely really isn't a option for me.
I'm assuming I take the large flywheel off and then I can get at the remaining belts.
My FF & Rew. work great!
But I may do what you said so it's works really well.

One thing that is kind of wierd I noticed that when on FF if you hit pause it pauses,I thought that was only for Play?

I just wish I had a regular work table to do this on-I have such a small house right now but I'll get it done.
This is really nice 9990 so I definately want to get this tape deck back to 100%.
I'm sure it willl be good as the speed was very close but that belt was slipping.
Those 2 belts were glazed!
Thanks again on this,now I just have to order some belts.
Have a great week-GB.

Jeff. Don't mess with the ciruit board. It's tethered all kinds of ways and the wires could break at the solder joints when handled too much.

You should have the chassis sitting on the back and remove the mechanical assembly from the front. I know -- it looks like it is blocked by the tuner dial. No problem. The tuner dial is clipped on, is all. Just unclip it and set it aside. You may need to desolder one ground wire on the dial. The LCD is removed and set aside. Put tape over it to prevent scratching it. Then you can remove the mechanical assembly and work on it. The SBL 5.4" belt is the most important one and the one you most likely missed. It is below the main flywheel and it'll have to come out. It's a little hard to do without a special belt hook tool. Make sure you clean all pulley surfaces with 100% alcohol (the 70% rubbing alcohol is not really strong enough). When the capstan flywheel is removed, the plastic capstan washer will likely fall off. Make sure you reinstall that when the capstan goes back in. Good luck.

Thank-You again Norm!! When I get my belts I will do this!
I've been working on it from the back.
You are a great helper on this site-I comend you for all your help & knowledge!
I'm truly happy that I did get the top 2 belts.
I'm going to order belts but it might not be for 5-6 weeks as the bills are coming up and not much work until March.
Then I will get this done and maybe 1 other like my 9191!
Slowly but surely I will get my 6-7 boxes that need tape deck work fixed!
BTW-I always use the 93% Isopropyl alcohol-I don't use the cheap stuff!
Have a super week-Jeff.