SL70/RD218 not showing targets

[cowbayalbin]

Thanks Chuck for getting back to me so quickly on that issue! Before I shell out the cash (more here in Canada) for a new system (don't think I'd want to spend money on replacing major parts of an obsolete system with questionable used bits) I'll take the unit apart and see if there's anything fairly obvious that appears fixable. Any idea which circuitry specifically might be suspect given the symptoms I described?