Some keys on the left side are not giving sound when played and the master volume is loosing can it be fixed or should i have to buy a new master volume

JUST REPLACE THE SPEAKER, IT MIGHT HaVE A LOOSE CONNECTION, As REPAIRING IT WONT GIVE U THE BEST OUTPUT.

If those keys work normally, it's hard to see how the key switches themselves can be bad.
Is your keyboard MIDI capable? If you play the same chords, does the MIDI output look OK?
Could it be that your keyboard simply can't play all of the different sounds at the same time? I know some are limited in how many simultaneous tones can be played.

Maybe try adjusting the MASTER level?

Good Luck

Other settings
Adjusting the master level You can adjust the level of the headphone and the stereo out by turning the MAIN VOLUME knob. The MAIN
VOLUME changes the analog signal level. This will also adjust the entire level of the MPC1000 digitally.
01. Press the [MODE] key and then the [PAD 10] (OTHER).
It switches to the OTHER mode.
02. Press the [F1] (GLOBAL) key.
The GLOBAL page will be displayed.
03. In the Master level field, set the level.
You will set the digital signal level, which will be sent out to the DA converter. The MPC1000 can output up to
32 sounds simultaneously. There is the great difference in the level when you play single sample and play 32
sounds. If you increase the value in the Mater level field, you can increase the entire level of the MPC1000 to
create more powerful sound with less noise. However, if you playback many sounds at the same time, the
level may be overloaded, which may cause distortion. If you decrease the value in the Master level field, you
can prevent distortion when you play many sounds at the same time. However, you cannot have a good
result in respect to the noise or punch of the sound. Set the appropriate value in the Master level field
depending on the application.

Go into function and look for the volume setting for your main voice - could be R1. This will give a numeric value of 127 or less. It sounds like you need to increase it, try 100 as that is usually sufficient.

The key contacts are dirty. Each key has two contacts to implement VELOCITY sensing. When a certain one fails to contact, then the note is sounded at full volume. The contacts are conductive rubber pills pressed onto circuit traces. Clean only with 99% isoprophyl alcohol and Q tips very gently. It takes a LOT of dis-assembly and care to do this. It might be better to take this to a repair shop. There is a possibilty that a liquid was spilled into your keys as well. Cleaning is the answer.

Do you turn on standby every time and wait for the tubes to heat up first? If you don't, it can severely damage the tubes.
But a common cause of this could be just old tubes. Like any other piece of technology, tubes get old. If you like to play your amp LOUD then they wear out a lot quicker. You have to replace tubes every now and then. Because I'm not there to check out your amp, I can't give you an exact answer but it sounds like that's the problem. This isn't always a bad thing. You can make the sound of your amp exponentially better with nicer, new tubes. Your amp has 12AX7 tubes. Very common tubes to use actually. I'm not sure what kind of music you play, I'm assuming mostly rock and blues. But here is a list of tubes and reviews on them.
http://thetubestore.com/12ax7review.html
This is how to replace a tube:
http://www.ehow.com/video_4438285_change-pre_amp-tubes-guitar-amps.html
Upkeep on a tube amp:
http://www.ehow.com/video_4438295_replace-tubes-guitar-amp.html
A note he doesn't make in the video is to dust out your amp. I use the compressed dust spray for the inside of computers.
So overall, stop turning up your amp to 11, make sure it's well ventilated and dust it out from time to time. Hope this helped.

Servicing is obviously required. By the symptoms, I think a bad electrolytic capacitor is the likely culprit. One other possibility is contamination, including an insect has gotten into the works and causing a short at some point.

This is the type of repair that should be done by a qualified service person.

dirty dirty dirty

give the knob a ********
can of compressed air should do the ttrick remember to remove knob if posable

I have a soloution that will work as long as you still have the metal shaft on it?
if it does go to your local electrical store and buy a new knob.
then all you have to do is screwthe knob back on to the amp.
please reply and tell me if that helps.