Inside the transport buttons

The row of five transport buttons is one of the simplest mechanisms on the machine — which is good news, because it makes it one of the most fixable. Here's what's inside, what breaks, and where the spares come from.

What's behind each button

Front of the transport button bracket with the caps removed: threaded bushings, lock nuts, and the white plunger tips

Each button is a four-part stack: the black button cap, a white plastic plunger rod, a black plastic mount whose threaded bushing carries the rod through the panel bracket, and an Omron V-series snap-action microswitch held to the back of the mount by two small screws. Press the cap, the rod slides through the bushing, the switch clicks. That's the whole mechanism.

One button assembly taken apart: microswitch, white plunger rod, threaded mount and its two screws

The part that breaks

The failure: the white plunger rod with its snapped tip, next to the button cap it broke away from — glue residue on both

The most likely failure is the white plunger rod: its thin tip snaps off. The cap is glued onto that tip — a small dab from the factory, on both my original buttons and the donor parts — so when the tip lets go it usually stays glued inside the cap, and the button can no longer drive the switch.

The BII donor harness

Wire harness from a BII with the same button switch assemblies on their bracket — drop-in replacements

I bought a complete wire harness from a BII, and its button assemblies are drop-in replacements — same switches, same mounts, same size caps. The one difference: my model's caps had the transport icons painted on them, and the BII caps are plain.

Part numbers for the hunt

Between my deck and the donor harness, two variants of the same Omron V-series switch turn up. This is the switch that was inside my machine — a V-10-1A8, still on its mount with the plunger rod through it:

The switch from this deck, on its mount with the plunger rod in place: Omron V-10-1A8, marked V3F1P01A — 10 A, 1/3 HP 125/250 V AC, UL-listed

The donor machines' switches carry the same V-10-1A8 marking alongside a second variant, the V-15-1A5:

Donor switch marking close-up: Omron V-10-1A8, marked V3F1P01A — 10 A, 1/3 HP 125/250 V AC, UL-listed

Donor switch marking close-up: Omron V-15-1A5, marked V4F1P01C 672010 — 15 A, 1/3 HP 125/250 V AC

• V-10-1A8 — marked V3F1P01A; rated 10 A, 1/3 HP, 125/250 V AC
• V-15-1A5 — marked V4F1P01C; rated 15 A, 1/3 HP, 125/250 V AC

Both are SPDT snap-action switches in the same body — and the V-15-1A5 is still in current production: element14 stocks it as Omron V-15-1A5. I haven't ordered one yet, but the ratings match the originals. One caveat if you go that way: the modern part is the bare switch — the white plunger rod, the plastic mount and its two screws aren't included. Keep your plastics, and let the new part supply the click.