Had exactly this problem yesterday. Had no idea how old these machines were! 1984. Anyway, slow fill in this case was caused by the a previous repairer switching the wires between the hot and cold solonoid valves. The hot valve has a restricter in it, the cold not.
Once switched back, it was fine. The 2 cold water solonoid wires have "cool" colours, the hot solonoid wires are "warm" colours.
have you got good water pressure to the taps in the rest of the house?(if yes) suspect inlet pipe to machine, turn off,water filler tap,remove hose from machine end,HOLD end in a bucket OPEN tap,pressure SHOULD BE THERE, is your tap one one of these self cutting type ? guarantee the tiny stupid hole is blocked change the valve.check and clean filter screens on the inlets to water solenoids
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