Lower Unit Noise?

[Matthew C]

Hey guys, I have a 99 115 2 stroke 'S115TLRX'. I took my boat with me on vacation this week to the beach and I'm hearing a rattling noise at low rpm's 'idle speed' whenever the motor is in gear. Before we left the house, I changed the gear oil with 90 weight Mercury oil that my dealer sold me and also changed both washers on the drain and fill bolts. The gear oil that came out looked good, wasn't watery or super thick, and I wasn't having any problems before I changed the oil...just changed it as yearly maintenance. Any ideas or suggestions? The noise actually sounds like it's coming from up top near the powerhead, but only comes in whenever the shifter is moved to forward. No reverse noise whatsoever. I also had the foot off last week to change impeller and housing, and everything went back together good. No problems with that repair. Any suggestions would be appreciated.
I did use the gear oil pump to put the oil in from the drain hole and not the top hole

[99yam40]

did this motor have the spring and flat washers over the water pump?
if it did did you pull up on the shaft when setting them in place?

[Matthew C]

It had 2 flat and 2 wave washers that sat on top of the water pump but no spring.

[99yam40]

wave washer is what i was calling spring washer.
it preloads the shaft/gears so that they do not make noise while idling in gear

[Matthew C]

Will this hurt anything until I get home to check it?

[99yam40]

no it is just annoying