Typing this for the second time!
Did I screw-up or was it the interwebs thingy?
Anyway,
SWR, or to give it its full name VSWR (Voltage Standing Wave Ratio) is a function of the load, ie the antenna and its associated feeder cable.
It is not a function of the transmitter.
Assuming that you are using an external SWR meter rather than something built in to the transmitter, any repairs and modifications to the transmitter will not make any difference to the SWR.
Having said that, it is possible that harmonics or other spurii from the transmitter will affect the SWR reading.
If changes are made to the low-pass filter between the PA stage and the antenna connector, the level of harminics/spurii could change and so change the SWR reading.
JimB