How did you get the exhaust springs out? To do it without removing the heads from the engine, you need a spring compressor, an air compresssor with an adapter to for the spark plug hole. Then bring the engine to TDC for the cylinder you are working on, pressurize the cylinder (around 85 lbs.) , remove the rocker arm, compress the spring, remove the keepers ( be careful not to loose them ), remove the spring, remove and replace the seal, replace the spring and keepers, release the spring, replace the rocker arm, and repeat for the next cylinder, etc., etc.
note: Sometimes you have to give the spring a sharp rap to release the keepers. I use a large screwdriver and hammer and give it as shot. I also place paper towels around the spring to catch a keeper if it happens to fall out.
While in there, replace the exhaust valve caps, a new set of springs won't hurt, and possibly new rocker arms, just be sure to prelube and torque them properly when reassembling. Don't leave the parts dry, **** them or you could ruin them on start up. Torque the rockers to around 25 ft lb. and recheck them after they have set for a few minutes.
Good luck,
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