To check the bearings, raise the wheel and try to rock it diagonally. Holding the tyre as close as possible to the top and the bottom helps avoid confusion with fork bush wear.
A soft drift or flat-ended punch can be used to undo the lock rings; both are right-hand thread and the brake side has the larger hole. To avoid damage use firm, carefully-aimed blows.
Drift out the brake-side bearing first – its spacer sleeve obstructs reaching the other side. There’s no centre spacer, this sleeve and the stepped axle separate the bearings.
A peg spanner is the best tool for tightening – this Triumph one fits. The notch at 12 o’clock is to punch the thread for locking. A dot of Loctite may be better.