Samsung DVD-VR350M 'hunting' disc?

Hello.

I've been given the above DVD recorder/VCR machine to try and sort, on a 'nothing to lose by trying' basis!

'Bought' DVDs play fine, but it really struggles with any recorded DVD regardless of format. It can't even cope with discs recorded and finalised on an IDENTICAL machine (the owner used this one for transferring his video camera recording onto DVD and the other acts as a 'normal' machine to record TV in his sitting room...) The symptoms are that it 'hunts' very noisily - lots of whirs/clicks - for the 'start' of the disc and it's pure chance whether it'll actually play it or not; you can often have some success by repeatedly reloading a disc.

I've used a lens cleaner - repeatedly - and have also opened the machine and gently targeted the lens directly with a cotton bud and alcohol (as I said, nothing to lose!)

No improvement.

Any ideas on what I can try next?!

Many thanks.