I just replaced the red gear that was destroyed in my DCC300 by buying it from the DCC museum. 
Well, comparing the reborn DCC300 with the DCC730, I noticed that, using first generation tapes, even used ones, they are perfectly recorded, without any dropout, by the DCC300, and reproduced just as correctly. If I play them on the DCC730, there are a lot of dropouts, making the tape unplayable. Even the second generation tapes are recorded and reproduced by the DCC300 very well, while sometimes in the DCC730 there is some hesitation. From this first test it would seem that the DCC300 is less sensitive to small imperfections, while the DCC730 is more intolerant. Furthermore, the 300 seems to sound much better than the 730, with a richer, clearer, more faithful sound. It’s possible? What do you think about?
Your DCC730 may need new pinch rollers and belts.
It could also be a tape speed problem. Does a analog cassette sound ok on the dcc 300 and 730? Just to test.
I have the problems that you have with all my 3rd gen players, and with my 2nd gen not so much. Replaced belt and rollers etc. Tapes recorded on them are not very ‘compatible’ on other decks.
But not everyone experiences this (fortunately), so your milage may vary 
It’s a pity, because I really like the turbo mechanism.
Yes, the 730 plays the ACC very well. I think however that, in general, the 2nd generation is much better, except the good turbo mechanism, than 3rd generation; these don’t even have the vu-meters…
Dear friends,
I can confirm the same issue related the drops on DCC’s of third generation . And taking the opportunity on life to have time now for several purchases including a great quantity of recorded cassettes around european online sales, I’m playing on two DCC730 that I purchased, after 30years of usage and I believe, with lots of analog cassettes, when playing the same Cassete on DCC 300 and 600 never happens these drops!
My first impression is that, recorded Cassetes are much sensitive if they’re recorded on different generation equipment.
Playing the DCC museum cassette of Ben Liebrand I get a perfect sound on all equipments.
Next test is to do some recordings over on these old cassettes with the 730 models and check again if this situation of drops happens after on the same equipment of third generation where was recorded.