the solenoids are mounted front and rear of cylinder head single 10mm bolt holds each in. the exhaust cam one is on front of head very easy to change 10 minutes tops, the inlet is a tad more of job airbox and rubber 90 degree inlet pipe remove ie 7mm jubilee clip both head,,, the vanos sprockets are correct name for them these are oil fed from the solnoids valves need 25psi min to work and state of engine oil makes a big difference to them,
i would very much doubt on a 66k engine these vanos sprockets would be faulty, i would however say 100% the timing chain is stretched and tensioner has gone weak,