The broken part
The failed part is a small white plastic bushing / shaft support located near the front of the drive.
Its job is simply to:
- keep the metal lever shaft correctly positioned;
- support the shaft inside the chassis;
- allow the shaft to rotate when the floppy latch is operated.
The part is not related to head positioning or track alignment, so this is fortunately a fairly low-risk mechanical repair.
Temporary repair
For now I managed to repair it using a washer.
This is obviously not a factory-quality solution and I would probably not trust it for a machine used every day, but for occasional use it works well enough.
The important points are:
- the shaft must stay correctly aligned;
- it must still rotate freely;
- the washer must not introduce excessive friction or sideways movement.
Since this Tandy is only used occasionally, this repair is good enough for the moment.
Dimensions for a future 3D-printed replacement
From measurements taken from the surviving plastic part, the dimensions appear to be very close to simple metric values:
| Feature | Approximate dimension |
|---|---|
| Overall length | 4.0 mm |
| Flange thickness | 2.0 mm |
| Smaller barrel length | 2.0 mm |
| Large flange diameter | 8.0 mm |
| Smaller barrel diameter | 6.0 mm |
| Shaft hole diameter | 4.0 mm |
So the basic shape can be thought of as:
- 8 mm diameter flange, 2 mm thick
- 6 mm diameter barrel, 2 mm long
- 4 mm central through-hole
- 4 mm total length
These dimensions are approximate and should be checked again with calipers before making a final CAD model.
For a 3D-printed version, the shaft hole should probably have some clearance. If the metal shaft is really 4.0 mm, a practical printed bore might be around 4.1 to 4.2 mm, depending on printer accuracy and material.
Another option would be to model the hole at 4.0 mm and drill or ream it afterwards until the shaft rotates freely.
A small chamfer on each side of the bore would also make installation easier.
Suitable printing material
For a permanent replacement I would prefer:
- PETG
- nylon / PA
- ideally SLS or MJF PA12 if professionally printed
PLA would probably work for testing, but the original part experiences repeated mechanical stress, so a tougher material would be preferable.
Possible donor drives
I also investigated using another TEAC drive as a donor.
The FD-55BR-501-U and FD-55BR-505-U are later members of the same general TEAC FD-55 family and may contain a compatible version of this mechanical support.
However, TEAC used different mechanical options and shaft lengths across the FD-55 range, so I would compare the parts directly before transplanting the complete lever-shaft assembly.
For such a tiny component, making a replacement is probably preferable to sacrificing a complete working drive.
Conclusion
The original TEAC FD-55BV-75-U is staying in the Tandy 1000 EX.
For the moment, the washer repair is perfectly adequate for occasional use.
If it fails again, the part is simple enough that a small custom 3D-printed bushing should be a much cleaner permanent solution.
Most important dimensions to remember:
Ø8 mm flange / Ø6 mm barrel / Ø4 mm bore / 4 mm total length, with each section approximately 2 mm long.