Komatsu D65e won't steer

I have 1978 Komatsu D65e-6 that I use on my farm for clearing. It had been sitting for a while and today when I cranked it up it won't steer. I pulled the covers on the 2 filter housings under my feet and filled them with hyd. oil thinking maybe the system had just lost prime, but nothing. I then cracked the bleeder bolt on top of both filters and one of them started spitting out oil but the other one never did. Any suggestions? Thanks

Komatsu D65e won't steer