Gp405 & Gp285

[songela]

Please Gentlemen,
Can anyone let me know the essential difference between the GP285 and GP405. I have got a broken GP405 and a working GP285; I would like to get the 40 cpm advantage on GP285 by using parts from the GP405. Please help!
Regards

[yourownfree]

swapping parts to get more speed just doesn't work