The MMC6000 cartridge was probably my favourite - less temperature sensitive than the later 20CL. It was however extremely sensitive to dust on records due to the contact line stylus designed by Subir Pramanik. I used to clean the record, then play it on the record player without listening, clean the stylus and then listen! Obscure fact - his wife worked at B&O and sometimes answered to telephone if you rang them! Lovely telephone manner! There was no 4 channel tape player - the connections were made in case you wanted to attach another makes 4 channel machine though this seemed unlikely. My BM6000 also had the BASIC sticker on - I suspect this was the standard fitting - Tim Jarman at Beocentral is the person to ask about whether there were any other types though I suspect there were not. There were two types of BC5000 though - a three head version and the later 2 head - the latter was slightly more reliable and the three head version was a strange device as the playback head was in front of the record head so no off tape monitoring possible. Having had a couple, they are certainly a challenge. The later 8004 is the cassette player to have! The 9000 has a clever tape calibration system but adds considerable complexity for very little return - in my time I have had them all and the 8004 was the best. On receivers, the BM3400 was possibly the best 4 channel receiver though obviously not as powerful, but was direct coupled unlike the 6000. The service manuals will be on site - the 6000 had a service manual and a technical manual which was fun. It is probably on site - I scanned them on for the original Beoworld site and suspect they will have been rescanned rather better! I do still have a couple of CD4 records though now are pointless!