damn man
them things are a pain in the ass.
ok.....
now, some say u cant replace them, that u have to buy a new TB because the TPS a set to the particular throttle body. and honda sets them for the factory.
it u take ur throttle body off, u will see that theres kno what it can come off....(says honda) so this is how they get u to get a whole new TB. but u can use any TPS from 89-up from any honda. honda or any auto part store does not sell them either.
u have to go to a junk yard and take one off the TB.
if u have an after market Throttle body then its easy to take off, i have an aftermarket so mine was helled in place with hexagon screws.
but it urs or ur friends is stock, then he has to either drill it off the throttle body, buy a whole new throttle body or get a saw or dremel and but a slit on the top of the screw holding the TPS to the throttle body, just enuff to get a flat head srew driver on it to screw it off, cause if u notice, the screw doesnt have a screw head.

once u get pass all that BS u have to set the TPS to the throttle body (thats if u go the route of just replacing the tps instead of buying a new throttle body)
to set it, u need a volt meter
place the TPS on the throttle body, screw it in a little, just enuff so that its snugg.
place the negative from the volt meter to the green wire i think, and hte positive to the red wire.
u should see a voltage.
thing about this is u have to kno what the stock voltage was, because if the TPS is being put on a different TB then it was on, the voltage is not accurate.
like mines....

i just had to replace mines a month ago, i went thru 3 TPS before i got it right, they break easily.
someone had told me that all honda TPS voltage should be set at .45v
well i set mine to that and it was all ****ed up. i have a 90 accord so i checked my other accord which is the same year, it was set at .83v
so i set mines to that and it ran perfect.
guess it depends on the make or motor

to set the TPS, once u have it on snugg u just move it counter clock wise or clock wise as neccessary. the voltage will either increase or decrease. u want to get it as close as posible to the recommended voltage for ur motor.
hope that help, like i said, the shits a head ache
if ur friend has the money i say just get a new TB
i would have but i paid 150 to get mines bored out and i didnt want to go back to a stock TB