Repair or hack options for Z-IV Developing timer.

I'm having some problems with my Zone IV Developing Timer, the one with the temp unit and that changes with the temp shifts. It started getting a bit tweaky, nothing new every now and then it would need the wires jiggled, but this time I noticed one of the phone plugs was cracked, the one that goes to the temp unit. I've properly replaced the plug, but the wires had a layer of oxidization and I fear that the whole stretch might be corroded. Problem here is that the non-plug end ends Into the unit, and I can't figure out how to replace the cord. I've read that Calumet/ZoneIV does not repair these anymore, and although the Timer Unit is still good and works in normal time, I'm also thinking that I maybe could just figure out a replacement temp sender. If anybody has any electronics ideas for me to try I'd be very stoked. I've printed with this timer for 10+ years and out here when it gets hot it really helps keep the consistency of my prints. I've also considered designing a new one, I don't think it would be as hard considering the advances in chips and such.

About one year ago I bought a replacement probe for this timer from Calumet. They probably still sell them.

What sort of sensor does it use: RTD or thermocouple - and then what sort of RTD (Pt, Iron, NTC, PTC) or thermocouple (K, E...)?

According to the original operation manual, it has Quote;

" The electronic design utilizes state of the art microchips in a careful and conservative circuit configuration. My component selection includes gold signal connectors, military-style tantalum capacitors, sealed 'cermet' controls, precision metal-film resistors, and temperature-stable polycarbonate timing capacitor."
"The temperature-sensing unit is a black epoxy casting in the shape of and inverted U, with the temperature-sensing thermistor embedded in the lower front edge..."
"We've used precision curve-confroming thermistors so that the temperature sensors are not only accurate, but identical (and therefore interchangeable"

This 'interchangeable' sensor is what I think I need. I talked to Calumet and they're going to look on the shelf to see if one is still around, but I think that may not have much hope. The unit is good and solid, and I don't think I'd be hurting any patent issues by perhaps figuring out some other way to get the temp info to the unit.

Zone VI made at least 2 separate designs of this probe. The one I obtained from Calumet is a stainless steel cylinder of 0.25-inches diameter x 7.0 inches long.

Wow, that's totally different than mine, which is the black chunk of epoxy. I managed to get mine to go properly, I replaced the phone connector again, and cleaned the whole temp unit. When I did that, the little lever had corrosion on the magnet part, and I cleaned that as well as re-magnitized it with a strong magnet. Fiddling with that lever in place and with the magnet in the proper position, I think made the sensors internal switch move correctly, and now the timing unit responds correctly to tempetarure shifts. I'm still thinking about replacing it with something better. I have no idea why this timer wasn't more popular, or why another manufacturer hasn't done another one, they are great in use.

They both had the same type of sencor in then. It was a 68 degree thermocouple.

Aha!
What's a 68 degree thermocouple?

they were very expensive when sold new. I seem to remember over $300 for a timer. I have one now. I like it.

lee\c