Ayuh,.... That appears to be an early MC-1,.....
Later MC-1s had the trim indicator in the up hyd. line, inside the transom,.....
I don't believe parts are available for the indicator mounted on top of the bellhousing,.....
Ayuh,..... Sure is,....
If you wish to explore further,.... Which motor,..?? Which drive,..??
Cable steering,..?? rack, or rotary,..?? Hydraulic,..?? P/S,..??
Ayuh,..... You have to up-date the lower shift cable to the Alpha 1 kit,.....
I believe those ole MC-1s use a drive bellows with a flat spot on it, but I also believe all that vintage MC-1s use the same bellows kit,....
Ayuh,..... Welcome Aboard,...... Maybe,.....
But we have no idea what type of steering you have,.....
If this is a V-hull, with an I/O drive, my guess is yer seein' v-hull wander,.....
Less operator input is the best cure for that,....
Ayuh,..... Welcome Aboard,...... Considerin' the standard range of prop pitches runs from 13" / 15" to 21" / 23", 'n you think the 21" on it is to small,.....
I'd look for another 21" or a 23" to test it out,....
Ayuh,....... Welcome Aboard,...... Back in the '70s, the reverse lock was mounted inside the transom, in the up hyd. line, not in the pump, like later systems,......
Ayuh,..... Are you planning to fix, 'n run it, or remove it to update it,..??
For any kinda manual to help, yer gonna need the Volvo manual for it,....
Ayuh,..... Welcome Aboard,....... Here in the I/O forums we don't care what the make, 'n model of the boat is,.....
But, what's very important is Which motor, 'n Which drive is on / in it,.....
Serial numbers are a big plus too,.....
Ayuh,..... Welcome Aboard,...... A rebuilt carb is only a rebuilt carb, til the very next time ya pump abuncha crud into it,.....
Like AD says, check the contents of the fuel filter 1st to see which direction to proceed,....
Ayuh,..... You just have to plug the passage 'tween the upper, 'n lower,......
Did you fog the 'ell outa the motor last fall,..??
If so, that might explain it,....
Ayuh,..... Welcome Aboard,..... There shouldn't be any screen anywhere near that fitting,.....
Readin' yer story, The switch, 'n pump should be powered by the ignition circuit, the purple wires,.....
Not from the alternator,...... which I believe is a Volvo trick,....