The main improvements over the last attempt were to increase the diameter of the pipe between the cold trap and the vacuum pump, and to improve the quality of the vacuum.

I bought new fittings for the vacuum pump with fewer narrow points along the path, and installed a bigger passthrough to the cold trap lid. It was hard to identify the thread on the body of the vacuum pump. I eventually worked out that it was a 1/2“ BSP. I couldn't find a 1/2” to 10mm barb fitting, only a 1/2“ BSP to 1/4” BSP and a 1/4“ BSP to 10mm barb. Not ideal. Scope for improvement here, but I don't think it's a huge factor.

Soon after receiving the vacuum pump I ordered some vacuum oil, knowing I'd need to replace the oil in the pump sooner or later. I figured I would drain the factory oil in the pump and replace it with the new stuff. The nameplate on the pump stated it should hold 370mL of oil. I turned on the pump and let it run for a while to warm up its oil, then turned it off and removed the fill and drain plugs. About 20mL of oil came out.

The oil level in the sight glass was about 1/3 from the bottom, and this level did not change when I drained the oil out. The oil was trapped against the glass by capillary action, and the pump had been running nearly dry for 25-30 hours. Not good. I poured in 370mL of the new vacuum oil and the level on the sight glass did not increase. I poured in about another 50mL until the level was halfway up the sight glass. The quality of the vacuum improved from around -0.98 bar to below -0.99 bar. The pump also ran much cooler.

I also used a newer, smaller, towel-lined esky to store the dry ice. Hopefully it lasts longer.

In an effort to waste less food and have less water to extract I only put in one thick slice of kiwi fruit and half a dozen blueberries. I forgot to take a photo, so here's DALL.E 2's impression.

I pre-chilled the food in the dry ice box before beginning. I set up the system with the food chamber in a water-ice-filled esky for the first 1.5 hours, then moved it to a 50°C water bath. About three hours after the start I noticed the blueberries had burst open and the insides were foamy.

A small splatter of blueberry juice is visible, but it had dried up.

The kiwi fruit developed a split across the middle.