It's fiddly to replace a DAC90A switch, but straightforward enough.
The video in post 38 only shows how to modify an old switch - enough of a faff itself - but why bother when for £1.50 or so, you can by a new Lorlin 2-pole six way switch which will fit in nicely, and remove the surplus tags? I'm not sure of the origin of the two diagrams I've attached below, but all credit to the originator. I'm surprised it's not more widely known, given that the wave-change switch on the DAC90A is a weak point.
The second pic makes very clear which of the five wires go where - how hard can that be?
Lorlin switch:
https://cpc.farnell.com/lorlin/ck103...26%20Solenoids
Hope that helps.