With age the surface mount capacitors on the U0DC-xxx Citizen Sam Drive will have already start leaking causing the drive to eventually fail to boot/read/write/format.
As with all capacitor leaks it is essential that the units are replaced and the corrosive electrolyte is removed before it damages the PCB.
Capacitor replacment in these models this therefore mandatory, a list of capacitors is available on the Replacement Parts List page along with link to Ben Versteeg's blog with details.
Thankfully the capacitors can be removed without having to fully dissasemble the drive, just remember to protect the other parts of the drive from heat when removing/refitting.
Quazar or Mutant Caterpillar Games can help with that if you're not keen on soldering surface mount components.
Drive heads can become clogged with debris from either the environment or from the surface of degraded floppy disks.
For all drive types, open the case and clean the drive heads using isopropyl alcohol and a foam/chamois bud (not cotton).
With age the drive belt in Citizen and NEC drives can stretch, break or even turn into a gelatinous mess depending on it’s composition.
A suitable replacement belt is a 71mm diameter flat belt 2.8mm high and 0.6mm thick although there have been reports of mixed reliability.
To replace the belt you must remove the drive from its plastic shell, unscrew the metal shield and the motor bracket to get access to the drive flywheel.
Clean the drive thoroughly to remove dust and fluff from the unit, clean the edges of the flywheel, jockey wheel and the motor spindle with a suitable cleaner such as isopropyl alcohol on a cotton bud - also check the drive head worm gear for fluff build up and re-grease if required.
Take the opportunity to clean the drive heads using isopropyl alcohol and clean the skid plate under the head assembly.
Fitting the belt can be done as demonstrated here but it can be done without having to remove the drive cage if you have two pairs of tweezers to hold the belt:
With the drive slot facing you:
- As above post cleaning with the top and bottom sheilds removed and the motor assembly popped out.
- Place the new belt around the flywheel.
- Using one pair of tweezers grip the belt about 10mm from the loose end so that it forms a small loop and bring the left side of the belt around the outside and under the silver jockey wheel and to the right hand side towards the right of the post so that they come almost together.
- Bring the loop to the hole below where the motor spindle sits.
- Bring the other pair of tweezers up through the hole and grip the belt loop and release the first pair of tweezers.
- Whilst holding the loop from the bottom, drop the motor back into position, guiding the motors pulley through the loop you are holding, push the loop up as you bring the motor down and it should hook on.
- Screw the motor assembly back down.
Alternatively see the picture below by John Lannigan from the AMSTRAD 8BIT COMPUTERS (PCW8256/8512) & CPC-464/664/6128 Etc.Group.
These can be 3D printed for either a 3.5" standard PC drive or a blanking plate see https://www.thingiverse.com/thing:873336/files