HP 6510p Touch pad woes

First off, I am a 'newbie' here and may well be posting in the wrong place. I picked here because I have been assured that the 6510p is a 'Business Class' laptop.

I bought a cheap HP 6510p with a 60Gb hard drive, which I promptly upgraded to 320Gb, and a worn out touch pad and keyboard - both very well used. The LH pad button had worn right through so I decided to replace the whole top panel and pad (that appearing to be the only option, I could not get a replacement touch pad on its own). The keyboard will be replaced later, it is only cosmetic with parts of key symbols worn away.

At the same time, as the beastie was in bits, I upgraded the cpu to a T7500 (from a T7250) and changed the 512Mb ram under the keyboard to 1Gb.

I checked the base top covers were the same part number (they were) because the one I removed had an Intel 'Core2 Duo' sticker whilst the new base top cover said Intel 'Centrino Duo', which kinda confused me a bit. The old cover also said rev 1.2 and the new said rev 1.5.

Having got it all back together and run it up after accepting the warning about the RAM size changing, I have found the new touch pad to be virtually unusable. The pointer jumps all over the screen when I move my finger about on its surface.

I have refitted the original hard drive (which I cloned on to the new drive) and with it fitted the touch pad behaves exactly the same as with the larger cloned drive which seems to rule out the driver going corrupt somehow. I then deleted the Synaptics driver (which was up to date) and installed V9_2_5vis32 version driver, which is slightly older than the original one. The change in driver did not make a scrap of difference.

So the question is - have I got a duff touch pad on my new base top cover, or am I missing something obvious ? Do the touch pads need to be 'trained' for a new user, or 'run in' in some way ?

Advice from forum members, who probably have oodles more experience than myself, would be much appreciated.

 

Right, a bit more data for you all.

I have taken the laptop apart again and refitted the T7250 processor and original base top cover. So now I am back to original configuration except for increasing the RAM to 2Gb from 1.5Gb. (like they say, when debugging only do one step at a time)

The result was the touch pad worked normally, no problems. Next I tried the new base top cover and that worked OK also.

This seems to suggest that replacing the processor screws up the touch pad operation somehow. The only difference I can see between the T7250 and the T7500, apart from clock speed, is that 'embedded options and 'idle states'' are supported on the T7500 and the voltage range is slightly wider. Both have the same core (Merom)

I have an Intel T8100 I could try, does anyone think that it would be OK ? It has a later core(Penryn) but does not have the 'embedded options' enabled although the 'idle states' is enabled.

The bios on this machine is F20, if that helps.

Thanks

Update. The T8100 causes the same problems I have using the T7500. Staying with the T7250(as fitted originally) as I know it works OK then.