My advice is if it ain't broke, don't fix it. I know of 11 Pips (8 of them Pip 2's). Only 3 of them are working properly. 2 belong to me, and one belongs to Owen Jones. To be fair, I don't know that one of them, which was advertised on this site, but the owner had contacted me because it had a fault which blew out tweeters, hasn't been repaired. If it is not banging crashing dropping out or otherwise malfunctioning, then it no more needs a service than does Marks Krell. Most of the non-runners, are on a shelf in Arthurs factory, who keeps asking me for help getting them fixed,
so well-meaning advice to consult Funk Firm is not very helpful. When I tried to get an experienced engineer, who has a well-established repair business to repair mine, before Owen sorted it out for me, he not only failed, but made circuit modifications in error. I am not saying nobody else can fix them. I am saying I know of nobody who has done so, and many that have either been damaged or just not repaired.
Replacing the battery pack, if that is knackered is VERY easy. The small control board (on the right, looking from the top) comes out with three screws and 4 wires. Where it connects to the main board your new supply needs to supply +18v, 0, -18v. Or, there is a bridge rectifier and smoothing capacitor on the main board - and just get a suitable toroidal to supply AC to the BR pins. Make sure the transformer ground is to the chassis ground, and not the star ground points. The big (100 ohm/ 1 watt?) resistor is to go in series with the switch light if you want that. Owen and I are using it in that format. A great deal of the "power supply" is integral to the amp. There is separate voltage regulation on the front of each gain stage. And the transconductance design effectively means that any voltage ripple on the supply rail is attentuated to "vanishing" on the output. So it shouldn't really need a fancy power supply. The Battery supply, as I have said many times, was primarily to justify the necessary price hike.
So, if it aint broke, don't fix it. If it is broke - not working - not usable,
then I guess you have to ask Paul Stewart which amp and phono stage he recommends as better, since he is confident he can assist you. I am not clear when he last heard a Pip 2, or what he has directly compared it with, since he declined to reply when I asked him, but he uses valves and a SUT for his system, and therefore maybe he has different tastes to me. There must surely be plenty of excellent alternatives - I just didn't find any. But then I didn't look very far, cos I'm a lucky b***ard and knew someone who could sort me out with a Pip instead.
And I'm very happy with it.
Be careful - if you have a runner, don't wreck it.