For my vacuum pump, I designed a timer, which switches on the pump every 5 minutes for a short time. This is just enough to avoid the loss of vacuum caused by small leaks. So, don't worry about small leaks that you cannot find, the vacuum remains in tact and the vacuum process can be continued.
Extreme long duration 555 timer without electrolytic capacitors
The two timers have a duration time of about 270s and 7s. By using a high resistance value of 1GΩ, no electrolytic capacitors are required. The 1GΩ resistor RGP0207CHK1G0 is available at Mouser for about €0,50.