The sampling diode is socketed. Why? It can easily get damaged, especially if the input is not terminated when in use. Let's hope this one is good.

The sampling didodes can get easily damaged, when the input is not terminated.
But this is not the sampling diode.
https://w140.com/tekwiki/wiki/Sampling_diodes

Vintage (?) tear drop or new SMD?

Sick again. Had some terrible terrible time. Ear infection on both sides with pain so bad I had to max out the daily dosage of prenoscription pain killers. Getting better, passing time with the new Lazarus Pokémon ROM hack

Actually, there were two bad tantalum caps. Who would've thought that these diode looking parts are tantalums

Let's dial back a bit though and start at the beginning.

Here's my (one confirmed working) 7000 mainframe.

Technology from 1972. 100 Mhz bandwidth with a pretty big and bright tube. Non-storage.

Tektronix was famous for their modular scope designs. The scope itself was just the screen unit and the power supply. Everything else was handled by plugins. The 7603 can take two vertical and one horizontal plugin. If these are input amplifiers or a time base is up to the user