mechanical Keyboards

[#1]

Any bright sparks have knowledge of mechanical KB ?
I have a Qpad http://qpad.com/products/keyboards/mk-85/
all is fine except the 3 ,4  ,  L  ,  M  ,  keys for some reason either miss the keystroke altogether  or they double type ?
have tried altering repeat rate but no change

[#2]

Go over it with a vacuum cleaner to remove any detritus from its insides and if that fails wash it with isopropyl alcohol.

[#3]

Be careful you don`t suck off the key tops though  ! 

If you do... you may consider one of these as replacement........  https://www.etsy.com/uk/listing/94663946/usb-typewriter-computer-keyboard?ref=unav_listing-same
or this.... cheaper version.....  http://www.cnet.com/uk/news/go-way-retro-with-this-mechanical-typewriter-computer-keyboard/

[#4]

Turn it upside down and shake it.
Mechanical keyboards are super-robust (or at least the original IBM XT was!)
If built to IBM standard, you could consider removing the key-caps and cleaning with cotton buds).

[#5]

Cheers , think will try the cotton buds 

[#6]

by any chance any liquid damage to it? I had that issue with an old Filco TKL board, built like a brick but spilled a huge cup of tea on it, only stopped the esc key working though, resoldered a new switch and good as new

[#7]

No nowt spilled on it , been working fine till recently