Once you discover what the main lever is and what it does, the pimpel's task will become obvious
The main lever rocks back and forth to raise and lower the arm and rotates side to side to move the arm around. The flattened end engages with the arm's lower assembly when auto-cycling and the dratted pimpel is the little rubbery bit that connects with it, needing friction and grease in equal measures to work properly. After twenty five years or so, this rubbery 'pimpel' hardens and eventually crumbles away, leaving a spring loaded 'pin' to engage with the main lever. this pin doesn't have enough contact area to move the arm laterally when asked to by the main lever so the arm usually raises and drops back down again, with often no lateral movement at all...
mrow2 (Don) here supplies fresh pimpels (mine needed lightly trimming, but I think he's sorted it now), together with the original recommended Alvania grease (if you decide to use a different grease such as Super-Lube or whatever, you'll need to totally remove the previous stuff) and a neat info sheet with pictures on how to do a basic service - unless you're very unlucky, the 601 shouldn't *need* a total strip down yet apart from the motor to check and lubricate the bearings... Even the main bearing on mine had some runny oil left in the bottom..
Hope this helps. Nice old deck the 601 with a superb tonearm that'll take most expensive cartridges out there (under a grand anyway) to good sonic effect - the M20E many came with is absolutely superb and needn't ever be changed as proper styli can still be got for it. Worth getting a new drive belt for it and if the pitch control is treated gently, you may not need a pitch belt - mines stretched a little, but hasn't broken up yet so I've left it alone for now.