Sony SLC9UB DC-DC converter problems?

I have a Sony SL-C9 Betamax VCR (UK model). When I got it, the display didn't work and neither did the tuner. Following instructions on Palsite.com, I rebuilt the DC-DC converter and now the display works, but with all segments permanently lit, and the tuner works (well it tunes in), but you can't select different programmes via the front panel or remote. Also, it won't go into standby, you have to switch it off with the mains switch at the rear. I am an electronics engineer by trade but not specialising in consumer electronics so I would be grateful for helpful advice from any more knowledgable folks! Thanks.