Hi,
I definately plan to continue and finish this service turorial. After a week of working with 4 different transports and 3 different decks on the (small) bench, life started getting a little miserable and the project started loosing it's appeal. Plus, I ended up needing some parts - my original donor transport ran out of bits and pieces to transplant.
The transports depicted on this guide are identical to the DTC59ES so the guide is totally relevant to your unit - it actually started on this deck.
From your description of the fault, it looks like the rotating gear that enganges the supply or take up spool on the transport doesn't work properly. This can be caused by dirt in the transport (as the deck is rather old), a weak spooling motor or too much tension in the spooling motor belt.
It might also be caused by a failed attempt to repair something. I've had two cases of such problems and these were the really easy ones to fix. One needed cleaning to remove tons of grease and the other needed replacement of the tape load arm location switch sensors.
In the week that passed since my last post on this, I did a little more work that I keep notes on but didn't post it as it mainly involves myself running in circles mostly.
I have "modified" a transport and removed the breaks and tension pads (that needed replacement). This transport has no breaks, no back tension and was thorougly cleaned and carefully lubed. It should have minimum of friction and tape travel should be nice and easy.
I have found that even this transport struggles to FF/REW a tape. 60 min tapes are ok, but 120min are moaning and 180min tapes struggle and 240min tapes don't make it to the end of tape.
Now, I know what most people write about 90 and 120 meter tapes and DAT machines (they are not compatible), but having 2 professional DAT units use them like a charm and also a couple of fully repaired consumer versions (DTC 670 and DTC55) doing the same, it feels like the concensous is a result of lots of units in bad shape having the same problem.
Anyway, I have just received a small lot of spooling motors at $3.95 each and I am planning to replace the motors on two transports that I cannot find anything else wrong with.
I am also doing some experiments on refitting tension pads where the original ones were reduced to a muddy lot of sticky substance and had to be removed. Without them there is no back tension and I can either over tighten the tension arms and get decent play but no FF/REW or keep them loose and get good FF/REW (too good and the deck stops thinking the tape is ended) but having no back tension it leaves me with playback problems as the tape get's curled off the capstan/pinch roller.
I am also looking for a source for pinch rollers. I am expecting a faulty computer DAT drive that might be a source for parts. The Dutch supplier Warren suggested seems to have everything but at 5 euro for bits and pieces each and 38 euro for a pinch roller, fixing a $20 faulty unit makes no sense.
I will be back in a few days (next week most likely) with some more feedback and progress. Most likely I will document the full stripdown of the transport for cleaning and lubrication. This has fixed 10 decks for me already and it is the hardest cases that were left when I started this thread, so perhaps the problems of these last decks are uncharacteristic of the majority.