I will post up my diagram and step by step explanation of it in the mean time.
We are told that there are 6 technicians and that each will perform at least one of three repairs.
So we do know that each technician must perform a repair, but we do not know as of now that every single repair will be used. In a situation like that, the inherent sense of order can be seen with the technicians being the base of the set up. We know each technician must have at least one repair, possibly all three. We simply do not know until we reach the rules.
The first rule tells us that X and three others do repair R.
Notice that I place the R with the X and I denote that I have three R's remaining to place. Five contenders for those three R's. We know X has repair R, but we do not know that it is ONLY R, it could be more.
We know that Y does T and V. Y is not limited to those necessarily. We know that Y has those, but we do not know that it is ONLY those.
Our next rule tells us that S and Y do not share any repairs.
We only have three repair types: R, T, V.
We know that Y does T and V. That is 2 of the 3 repairs.
We know that each technician must do a repair. Since this rule tells us that S and Y share no repair in common, that means that S must have repair R. It also means that we can wall off Y and wall off S.
Those two technicians have their task lineup complete. There is no way that S could have any more repairs or that Y could. We also have one less R to worry about placing. We only have two R's left to place.
Our next rule tells us that Z repairs more than Y does. We know that Y must do 2 repairs. To have more repairs than Y it must do all three repairs. We can wall that off to show that this technician's selection is complete. We also have only one more R left to place.
Our next rule tells us that W and S do not share any repairs. We know that the only repair that S performs is R. Since W cannot do this repair, that means that the last R must be placed with U because there is no other place for this remaining R to go.
Our last rule tells us that U performs exactly two repairss.
We can wall off U with two repairs to be performed. We know that one of those repairs is R, so the other remaining one is one of T and V.
We know that W cannot do repair R, so the maximum amount of repairs it can do is two. We can wall off to show that it can only do 2 best case scenario. We know it must do one for sure, so I will show that with a slot, but I do not place a slot for a second repair because that is something that does not have to be true. I do know that W's task in that slot must be one of T and V.
Notice that X can have 1, 2, or 3 repairs.
U must have two, but we are not certain as to its makeup of that second repair.
We know that W's repair lineup consists of either 1 or 2 repairs.
The rest of the field is complete.