Understanding valve seals

so we ran a boroscope on all cyl. on drivers side and saw what look like small drips on cyl #5 piston. Swapped out
int/exh. seals. Don't see smoke on the road but tapping the pedal and get a little puff on this side. Going to change all seals on this side this wknd.
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How did you keep the valves from dropping during seal change??