If the problem is because the foam surround on that small driver has deteriorated then all you need to do is pull that driver and have the foam surround replaced on it. The foam surround keeps the cone centered as it travels to produce sound. Once the surround starts to fail the cone will not be centered and start to rub. A good speaker repair shop can do that. If you are a DIY type person then you can purchase a replacement surround and make the repair yourself. 

-sonavor

I already did the foam surround on this ages ago and it was fine.

When the distortion happen a few weeks ago i thought the same so i brought new foam and glued it hoping it would center it but no luck.

The speaker says on it 78 04 14

Anyone know what brand this is?

I searched the numbers in google but no luck

The numbers are a date code - april 4 1978.
It's a Peerless KU45MRF - unique to this model (and Beovox M100).
You won't find it elsewhere.

And it's really a "Filler" unit rather than a midrange in the conventional understanding.

They rarely fail - apart from the foam surround.
Most likely a misalignment when it was refoam'ed.
Was it professionally refoam'ed? Shim'ed correctly?

Martin

I brought the speakers on ebay with this drivers needing refoam i did it myself both mids worked fine for a good few weeks then this one failed and starting making voice coil rubbing distortion sounds.

So then i took the foams of brought new ones and glued them but distortion sound is still there.

I have done about a dozen refoams before i dont do anything fancy about centering them i just concentrate on the outline of the speaker and put the foam on neatly.

I have brought parts from you before, shall I send this to you for repair?

Very interesting you call it a filler instead of midrange, I cut the wire off currently to disconnect it then i use the balance knob on my Accuphase amp and I can hardly hear any difference between the 2 speakers.

If any thing the sound is more clearer and cleaner more studio speaker like sound and I dont feel like i am hearing any less instruments or important sounds.

On ebay US there is a Peerless KO40MRF / K040 MRF 821385 8 Ohm 4" will this do ?

1 thing i did change just before i had this issue was the speaker cables from the amp to the speakers, I changed to very heavy duty cables that look like car jump leads!

I have Accuphase pre amp and Yamaha P2201 power amp which produces 250 watt per channel.

I have a feeling the cables let in more power to the speakers and messed some thing up the red over load light came on a few times too.

The overload light coming on has nothing to do with the cables to the speakers.
And anything upwards of 0,75mm2 doesn't make much sense unless we are talking about hundreds of watts, very long cable runs or particularly bad cable materials.

Martin

The cables did make a very noticeable difference to Bass it is a lot stronger.

Is Peerless KO40MRF a good substitute?