hifi engine

Need Nytech service data.

I seek the Holy Grail of service manuals/circuit diagrams. One for my Nytech CTA252 XD (series 2 - 1981 version) I've had it since new but it's been in storage 10 years and now that I've got my analogue groove back on and hooked it up again it's got some issues. ( crackling power-up,, noisy pots, hums and the odd POP! ) Anyhow the innards of these things are a triumph of mid-seventies, cutting-edge British hi-fi engineering and are as such totally incomprehensible and I'm loath to proceed without the afore-requested information.
Anyone out there able to help out a 1st time poster to this fine forum?
Regards - Louis.