Douglass High's Troubleshooting Your Macintosh says:

The SE's most common cause of failure is a little Eight thru-hole contact box labeled on the silk screen layer as either "L1" or "Filter." It's the "RF Choke Filter" for noise suppression and is a "very high failure item on all Macs." It's usually located behind the two controller ICs. Check the Choke Filter"s pins from side to side for continuity.

Most Macs newer than the Mac SE are also equipped with a 1-amp pico fuse.

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So this second highest failure component won't be present unless maybe if it's a later SE-DualFDHD version.

In terms of a short, the RF Choke Filter can act as a fuse.

I'm home on lunch, so that's all I can say for now, but there are testing procedures, more caveats, symptoms and diagnostics outlined. Sounds like component transplants needed for a terminally ill Mac SE to me, but the author says . . .

. . . the ADB transceiver chip on the logic board is not really a high-failure item. Usually it's the stuff between the port and chip that goes.

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He has a table of "Problematic Mac models and their high failure items" in the ADB section . . .

. . . for the SE:

R14____470 ohm_____Resistor

R15____1K ohm______Resistor

Q1_____2N3904______Transistor

What's the scoop on ADB spelunking in your library, trag?